MedicineLakex

 

Ent63: public health pest management

A Training Guide
Michael F. Potter and G. Mark Beavers Table of Contents
Preface .iIntroduction .iCockroaches .3Ectoparasites of Humans .6 Fleas .6 Ticks .8 Lice .11 Mites .12Bed bugs .13Mosquitoes .14Flies .21Wasps, Hornets and Yellowjackets .24Spiders .26Rodents .28Birds .32Itches, Irritations and Delusions .33 Federal and state regulations require that persons who apply pesticides meet minimum standards of competency. Information pertaining to general standards is contained in the CoreManual, Applying Pesticides Correctly: A Guide for Private and Commercial Applicators.
This training guide (Public Health Pest Management) was developed to help you meet thespecific standards for professionals engaged in public health-related pest control. Collectively,the two manuals contain information necessary to pass the Commercial Applicator CertificationExam, and become certified to use pesticides in Category 8, Public Health Pest Management.
Public Health Pest Management
A Training Guide
Michael F. Potter and G. Mark Beavers contaminate food, kitchen utensils, and other items, and theyleave an unpleasant odor. Because cockroaches move freely Insects, rodents, birds, and other pests cause billions of from filth to food, they can transfer microorganisms that cause dollars worth of damage to our food, health, and property food poisoning and other illnesses (Fig. 1-1). Many people each year. Losses resulting from insect and rodent damage to are also allergic to cockroach excrement and their cast-off stored food alone exceed $1 billion annually. Many pests also skins, resulting in wheezing, watery eyes, and skin rashes.
transmit disease. Cockroaches, flies, mosquitoes, ticks, fleas, Cockroaches enter buildings in various ways. They are rodents, and birds are directly involved in the transmission of often introduced in produce boxes, beverage cartons, or gro- such diseases as food poisoning, malaria, typhus, viral encepha- cery bags. Species such as the American and Oriental cock- litis, plague, and Lyme disease. Other pests bite or sting or cause roach also gain entry through cracks and openings around allergic reactions in the indoor environment. Finally, pests living windows and doors, and through sewer and drain lines. While in and around buildings are objectionable to most people simply cockroaches thrive where sanitation is poor, even the cleanest by their presence, detracting from the overall quality of life.
home or restaurant can become infested.
This manual provides useful information on the identifi- Cockroaches are flattened, brownish, fast-running insects, cation, biology, significance and control of pests impacting with long, slender antennae. There are three life stages: egg, public health. From a regulatory standpoint, the manual em- nymph, and adult (Fig. 1-2). The female cockroach produces small, phasizes the responsible use of pesticides. However, our greater brown, bean-shaped egg cases, called oothecae, that are depos- goal is to provide a broader understanding of public health pest ited in out-of-the-way places. Several nymphs emerge from each management, and encourage its implementation. This informa- egg case. Nymphs resemble adults except that they are smaller tion will serve as a reference long after the certification exam.
and lack wings. The nymphs gradually become larger and inhabit the same places as the adults. Cockroaches are prolific breeders.
Species such as the German cockroach are capable of producing Cockroaches are among the most common insect pests several thousand offspring in less than a year.
found inside buildings. They are especially troublesome wherefood is prepared and sanitation is lacking. Cockroaches arerepulsive to most people simply by their presence. They may Fig. 1-2—Life cycle of the cockroach (nymphs molt several times). Cockroaches are more active at night than during the day- time. During the day they generally remain hidden in small cracksand other dark, secluded areas which provide warmth and hu-midity. At night, they leave their hiding places and search forfood. Cockroaches feed on a wide variety of foods and will eatanything consumed by man. They also feed on such materials asglue, hair, soap, fabrics, and filth. Cockroaches readily migrate Fig. 1-1—Cockroaches contaminate food, transferring from one room to another along plumbing and electrical lines and bacteria and other pathogens. through cracks and openings within walls.
Fig. 1-3—Common structure-infesting cockroaches--Left to right: German, brown-banded, American, Oriental, and woods roach. Drawingsapproximate actual size of adults. Types of Cockroaches
darker with a tan stripe down the middle of the back. German There are more than 50 species of cockroaches in the cockroaches reproduce very rapidly, which is one reason con- United States, but only a handful infest structures in Ken- trol can be difficult. A single mated female can produce an tucky. Determining which type of cockroach is present is es- infestation of several thousand new roaches in less than a year.
sential in knowing where to focus your control efforts. The German cockroaches require warmth, moisture, and food, following descriptions will help you identify common cock- which is why they are most common in kitchens, bathrooms, roach species. (Refer also to Figs. 1-3 and 1-4).
and eating areas. Preferred hiding places include cracks and German Cockroach (Blattella germanica) is by far the
crevices under sinks and toilets; beneath refrigerators, ice most common and important cockroach species from the stand- machines, dishwashers, and stoves; next to trash containers; point of public health. Adults are light brown and about 1/2 and inside cabinets and pantries. German cockroaches also inch long, with two dark stripes running lengthwise along the congregate in clocks, microwave ovens, and other electronic shield-like area behind the head. The nymphs are smaller and equipment. When populations are large or food is scarce, Fig. 1-4—Pictorial key to egg cases of common domestic cockroaches. (Harold George Scott, Ph.D., and Margery R. Brown) they can be found in bedrooms, closets and other non-food species involved. A bright flashlight, inspection mirror (for areas. German cockroaches spend most of their time hidden in inspecting underneath, above and behind construction ele- cracks and crevices, but can be quite mobile. They often travel ments), and a set of screwdrivers, pliers, etc., to access equip- between rooms or adjoining apartments along utility pipes ment and other potential hiding places, are essential tools for and wires, and within wall voids.
conducting a professional cockroach inspection. The use of a American Cockroach (Periplaneta americana) is the
flushing agent, i.e., an insecticide containing natural pyre-
largest cockroach found in Kentucky, measuring about 1 1/2 thrin, can also help to reveal hidden pockets of cockroaches.
inches long when fully grown. It is reddish brown to brown, Pyrethrum is highly irritating to cockroaches and forces them with a pale yellow band around the edge of the shield behind out into the open. Sticky traps and glue boards are useful
the head. Adults have well-developed wings, but seldom fly.
tools for pinpointing areas where cockroaches may be hiding.
Nymphs are smaller and lack wings, but are otherwise similar Monitoring traps should be placed at strategic locations, such to the adults. The developmental rate of the American cock- as beneath sinks or behind refrigerators, and positioned flush roach is much slower than the German cockroach, usually against walls, corners, or at the junction of two or more con- requiring more than a year from egg to adult.
struction elements. When foraging for food, cockroaches pre- American cockroaches prefer dark, moist areas, such as fer to travel along edges and corners where two surfaces meet, in basements and crawl spaces. They are often found nesting rather than in the open.
in floor drains, sump pumps, pipe chases, and laundry areas.
Cockroach inspections must be performed in an orga- They also frequent boiler rooms, steam heat tunnels, and sew- nized, methodical manner. Otherwise, areas harboring cock- ers. During warmer months, this cockroach may be found out- roaches may be missed. This is especially true when inspect- doors and around outbuildings and woodpiles.
ing restaurants and other commercial food handling estab- Oriental Cockroach (Blatta orientalis) is shiny black or
lishments where there are countless cracks and crevices in dark brown, and the adult is about 1 inch long. Females have which roaches can hide. A systematic way to inspect these very short wings; males have wings that cover about half the facilities is to begin at a door or corner and inspect one 3- to 5- abdomen. The entire life cycle may require one to two years.
foot "zone" (extending from floor to ceiling) at a time. Con- The oriental cockroach is one of the filthiest cockroach tinue in this manner around the entire perimeter of each room species because it commonly infests cool, dark, damp places (kitchen, dining area, etc.), inspecting sinks, ovens, dishwash- (e.g., sewers and basements), feeding on garbage, human ers, cabinets, and any wall-mounted fixtures or equipment.
waste, and decaying organic matter. The nymphs and adults You will also need to make periodic "sidetrips" toward inner are comparatively slow-moving and are generally found at portions of rooms, i.e., away from wall areas, to inspect equip- ground level. They often are found living in floor drains and ment, tables, etc.
sump pumps. During warmer months, oriental cockroaches Cockroaches are best controlled using a combination of also live outdoors beneath leaves and plant mulch.
techniques. Since roaches flourish where food, moisture, and Brown-banded Cockroach (Supella longipalpa) is far
shelter are readily available, sanitation is an important step in
less common than the German cockroach, but can be a prob- preventing problems. Crumbs, spills, grease, and other food lem in homes. Correct identification is important because it debris should be cleaned, and unwashed dishes, kitchen uten- has markedly different hiding places and habits from the Ger- sils, and pet food should not be allowed to set overnight.
man cockroach. The brown-banded cockroach is similar in Loose food should be stored in tight-fitting containers, and size to the German cockroach, but lacks the dark lengthwise garbage, cardboard boxes, and paper bags should not be al- stripes on the region behind the head. Instead, there are two lowed to accumulate. Items in food storage areas should be transverse yellow bands across the base of the wings.
removed from cardboard boxes and stored off the floor on The brown-banded cockroach prefers to feed on starchy stainless steel racks. Moisture leaks should be repaired and materials and may be found anywhere in a building. It does floor drains routinely sanitized.
not require the close association with moisture, characteristic Another element of cockroach management is exclusion,
of the German cockroach, and is more often found in homes also known as pest-proofing. This involves the use of seal- and apartments than in restaurants and other commercial food- ants such as caulk, foam, copper mesh, or cement. Sealing handling establishments. In homes, brown-banded cock- cracks, crevices, and other openings likely to harbor cock- roaches are commonly found in rooms other than the kitchen roaches eliminates the need to repeatedly treat these areas and bathroom. Preferred locations include upper areas of ceil- with insecticides. It is also a good idea to caulk or plug any ings, walls, cabinets, and closets; behind picture frames and openings where plumbing pipes or wires pass through walls wall decorations; and beneath or inside furniture. This roach or floors. This is especially useful in apartments to reduce attaches its pea-sized egg capsules to hidden surfaces, such migration of cockroaches between adjoining units.
as the undersides of dressers and tables.
Although good sanitation and exclusion are important, insecticides are usually required to eliminate an existing cock- roach problem. To perform the treatment safely and effec- Since cockroaches may be hiding in a great many places, tively, care must be given to the type of insecticides used and a thorough inspection is essential to locate as many of these
how they are applied. Cockroaches spend very little time out areas as possible. In performing the inspection, consider the in the open. Consequently, emphasis should be on finding
unique habits and preferred harborage sites of the cockroach and treating cockroach harborages, rather than treating
along baseboards, wallcoverings, and other exposed surfaces.
be read in their entirety. Some products can only be used in Besides being more effective, directed placement of insecti- "non-food" areas such as garbage rooms and mop closets, cides into cracks, wall voids, and other hidden locations en- where foods are never processed, prepared, served, or stored.
sures that residues will not contaminate food or food prepara- Other insecticides can only be applied into cracks and crev- tion surfaces, or be contacted by children or pets.
ices to limit potential contact with food or food preparation A wide variety of insecticide active ingredients and for- surfaces. As with any insecticide application, the label is the mulations is available for cockroach control. Residual insec-
ticides are commonly used and provide effective residues last-
ing from a few days to several months. For these products to
Ectoparasites of Humans
be effective, cockroaches need not be present at the time of Several species of insects and related pests feed on people application. The roaches are killed provided they remain on a and their pets. These pests are called ectoparasites when
treated surface long enough to absorb a lethal dose of insec- they feed externally, taking blood from their host. In addition ticide. Common classes of residual insecticides include the to the irritation caused by their bites, some ectoparasites such synthetic pyrethroids (e.g., cypermethrin, cyfluthrin); orga- as fleas, ticks, and lice also may transmit serious disease- nophosphates (e.g., chlorpyrifos, acephate); carbamates (e.g., propoxur); and inorganic dusts (boric acid, silica aerogel).
Residual insecticides known as insect growth regulators
(hydroprene, fenoxycarb) are also used in cockroach control.
Fleas are small (1/16"), wingless, blood-sucking insects These materials disrupt the cockroaches' normal growth and that commonly feed on pets and people. Their bodies are development, causing the population to decline.
flattened from side to side, permitting easy movement through Residual insecticides may be formulated and applied as the hairs of the host. In addition to causing discomfort and liquid or aerosol sprays, dusts, granules, or baits. Liquids and irritation, fleas can transmit serious diseases to humans, most aerosols are typically used for injection into cracks and crev- notably plague and fleaborne typhus. Fleas become carriers (vec- ices, whereas dust formulations are used primarily for treating tors) of these diseases after feeding on infected rodents such as wall voids and hollow spaces beneath cabinets and appli- rats. Fortunately, plague and flea-borne typhus are seldom en- ances. Baits are also used widely in cockroach control and countered in Kentucky. Fleas are, however, capable of transmit- contain such active ingredients as hydramethylnon, ting tapeworms from pets to people. Fleas account for more than sulfluramid, boric acid, and abamectin. Cockroach baits con- half of all dermatological conditions requiring veterinary assis- tain a slow-acting insecticide incorporated into a food attrac- tance, and even a single flea bite to a hypersensitive animal or tant. Roaches locate and feed on the bait and crawl away to individual may cause intense itching and irritation.
die, usually within a few days. Bait carried back to the nesting The most common flea that infests structures in Ken- area also kills other roaches after being expelled in the sputum tucky is the cat flea (Fig. 2-1) which feeds on both dogs and and feces. Some baits come pre-packaged with the insecticide cats. The dog flea, mouse flea, and rat flea are also sometimes and food attractant confined within a plastic, child-resistant con- encountered, especially where there have been no pets and tainer; others are formulated as pastes, dusts, granules, or gels.
the structure has had an infestation of rodents, squirrels, or Since baits must be ingested to be effective, they must be placed other wild hosts. If the host dies or is removed from the home, within a few feet of where cockroaches are likely to be living.
Non-residual insecticides are those products applied to
obtain control of cockroaches only during the time of treat-ment. Pyrethrin or resmethrin are often used in conjunctionwith residual products to locate and "flush out" hidden infes-tations of cockroaches. They can also provide rapid (althoughshort-lived) knockdown of cockroaches present at the time ofapplication. Non-residual insecticides are usually applied withaerosol or ultra low volume (ULV) equipment, and directedinto areas suspected of harboring cockroaches. Indiscriminant Fig. 2-1—Cat flea dispersal of non-residual insecticides into the air (i.e., foggingor space treatment) in kitchens, dining rooms, storage areas, the adult fleas will actively seek a new host. Some of the worst etc., should normally be avoided because it will only disperse problems with fleas occur when a family moves into a home and drive cockroaches deeper into wall voids and other pro- that previously had pets, or after an infestation of rats or mice tected locations.
has been eliminated.
Because cockroaches are typically found in areas where The life cycle of the flea consists of four stages: egg, food is prepared or stored, special care must be taken not to larva, pupa, and adult (Fig. 2-2). Adult cat fleas lay all of their contaminate food, dishes, cooking utensils, or food prepara- eggs (up to 50 per day) on the animal. The eggs soon fall off
tion surfaces with insecticides. Before treatment, these items into carpeting, beneath the cushions of furniture, and wher- should be removed, placed in plastic bags, or covered with ever else the pet sleeps or spends most of its time. Several hundred eggs may be laid by a single adult female flea.
Before treatment, it is essential that all insecticide labels After hatching, the larvae feed and develop on organic de- treatment. The most effective formulations contain both an
adulticide (e.g., chlorpyrifos, permethrin) effective against the
biting adult stage, and an insect growth regulator (e.g., methoprene
or fenoxycarb), necessary to provide long-term suppression of
the eggs, larvae, and pupae. Most homeowners will find aerosol
formulations easier to apply than liquids. Examples sold over the
counter include Siphotrol Plus®, Fleatrol®, Basis™ House
& Kennel Aerosol, and Raid Max® for fleas. It is essential that
the application be thorough and include all likely areas of flea
development. Carpets, throw rugs, under and behind beds and
Fig. 2-2—Life cycle of a flea furniture, and beneath cushions on which pets sleep should allbe treated. Pay particular attention to areas where pets spend bris, especially adult flea feces (dried blood), which accumu- time or sleep, as these will be the areas where most flea eggs, lates along with the eggs in animal resting and bedding areas.
larvae, and pupae will be concentrated. Hardwood and tile floors Larvae remain hidden deep in carpet fibers, beneath furniture generally do not require treatment, but should be thoroughly cushions, and in other protected areas. Before becoming vacuumed and mopped.
adults, the larvae transform into pupae within a silken co- Pet owners should expect to see some fleas for 2 weeks
coon. Pupae remain inside the cocoon for 2 to 4 weeks, some- or longer following treatment. Provided all infested areas
times longer. The pupal stage is relatively resistant to insecti- were treated initially, these "survivors" are probably newly cides, which is why some adult fleas are seen for an extended emerged adults which have not yet succumbed to the insecti- period, even after the home and pet are treated.
cide. Instead of re-treating the premises immediately, they Adult cat fleas (the biting stage) spend virtually their should continue to vacuum. As noted earlier, vacuuming stimu-
entire life on the animal, as opposed to in carpeting, pet bed- lates the insecticide-resistant pupae to hatch, bringing the ding, etc. This is why effective control of fleas requires treat- newly emerged adults into contact with the insecticide sooner.
ment of the pet in conjunction with treatment of the premises.
If adult fleas continue to be seen beyond 2-4 weeks,retreatment of the premises (and pet) may be necessary.
Effective flea control requires a systematic program con- TREATING THE PET
sisting of inspection, client education, treatment of the pet, It is important that the pet be treated in conjunction with the and treatment of the premises. Prior to treatment, the pet owner premises, preferably on the same day. Adult fleas spend virtually their entire life on the animal—not in the carpet. Untreated pets • Remove all toys, clothing, and stored items from floors, under
will continue to be bothered by fleas. They may also transport beds, and in closets, in order to provide access for treatment.
fleas in from outdoors, eventually overcoming the effectiveness • Remove pet food and water dishes, cover fish tanks, and
of the insecticide applied inside the home.
disconnect their air pumps.
Pets can be treated either by a veterinarian or the pet • Wash, dry clean, or destroy all pet bedding.
owner. A variety of on-animal formulations are available that • Vacuum all carpets, floors, throw rugs, and upholstery, espe-
may be prescribed by veterinarians. Some contain an insect cially in areas where pets rest or sleep. Vacuuming removes growth regulator (IGR) to prevent eggs from hatching as they many of the eggs, larvae, and pupae developing within the are laid on the animal. Two such products are Ovitrol Plus® home. It also stimulates pre-adult fleas to emerge sooner from and Basis™ Flea and Tick Spray. These products kill both their insecticide-resistant cocoons, thus hastening their con- adult fleas and flea eggs laid on the animal. Another very tact with insecticide residues in the carpet. By raising the nap effective product is the Ovitrol Flea Egg Collar. Although the of the carpet, vacuuming improves the insecticide's penetra- collar contains no adulticide, it prevents flea eggs from hatch- tion down to the base of the carpet fibers where the develop- ing for several months. For optimum results, the collar should ing fleas live. Vacuuming should be thorough, especially in be placed on the pet before flea season begins (April - May).
rooms or areas where pets rest or sleep. After vacuuming, the Similar results can be obtained with a product called Pro- vacuum bag should be sealed in a garbage bag and discarded gram®, which is administered orally to pets once a month as a in an outdoor trash container.
tablet. When a female flea bites a Program®-treated animal, Treating the Home - Once fleas become established in a
the flea ingests the active ingredient (lufenuron), which then home, insecticides are almost always needed to control them.
passes into her eggs and prevents them from hatching. Like Always read and follow label directions on the insecticide the Ovitrol Flea Egg Collar, pet owners should ideally begin container. Other than the person performing the application, using the tablets before flea season begins. Doing so will people and pets should be out of the house during treatment.
greatly reduce the chances of developing a serious flea prob- People and pets should also remain off treated surfaces until
lem later in the summer.
the spray has dried. Drying may take several hours, depend-
Pet owners should always read the pesticide label. Certain ing on carpet type, ventilation, and method of application.
products can be used only on dogs, and some list specific treat- Opening windows and running the fan or air conditioner after ment procedures for puppies and kittens. Do not treat pets with
treatment will enhance drying and minimize odor.
the same products used to treat carpeting or the yard. As men- A wide array of flea control products are available for home tioned, it is absolutely essential that pets be kept off treated The female then drops to the ground and deposits a mass of carpets and surfaces until the spray has completely dried.
eggs which hatch into thousands of tiny larvae. The larvae, To reiterate, de-fleaing the pet is an essential step in ridding often called seed ticks, disperse and attach themselves to a
a home of fleas; however, pet owners must also treat the pet's passing rodent or other small animal. After feeding, the blood- environment (the home). Having the pet dipped or using a flea
engorged larvae drop off the host and transform to nymphs. The collar will not, in itself, eliminate fleas in an infested home.
nymphs then crawl onto low vegetation and await another hostfor attachment and feeding before transforming to adults.
TREATING THE YARD
When not attached to a host, ticks remain on or near the Most flea problems in Kentucky can be eliminated by ground. Since they cannot jump or fly, the larvae, nymphs, treating the pet and the interior of the home. In cases where and adults climb onto tall grass, weeds, or brush to wait for a pets spend most of their time outdoors, it may also be neces- suitable host to pass by. Initial contact with humans is usu- sary to treat the yard. One way to determine if the yard is ally made on the foot, ankle, or lower leg. Once aboard, they infested is to walk around the property wearing white athletic crawl upward until constricted by skin folds or tight clothing, socks, pulled to the knee. If fleas are present, they will be seen often attaching behind the knee, waist, armpit, or base of the against the white background of the socks.
scalp. Ticks are especially common along overgrown borders Outdoor flea treatment should focus on areas where pets and paths, since these areas are frequented by passing hosts.
rest, sleep, and run, such as doghouse and kennel areas, under Ticks are seldom found in open areas of mowed yards.
decks, along fences, and next to the foundation. It is seldomnecessary to treat the entire yard or open areas exposed to full COMMON TICKS IN KENTUCKY
sun. Insecticide formulations containing chlorpyrifos (Dursban) The most common ticks found in Kentucky (Fig. 2-4) are or diazinon are effective for outdoor flea treatment. These can be the American dog tick (Dermacentor variabilis) and the lone applied with a hose-end or pump-up sprayer. Long-term sup- star tick (Amblyomma americanum). Both species readily feed pression of fleas infesting kennels or outdoor areas can be en- on humans and pets. Another species, the brown dog tick hanced with formulations containing a light-stable IGR such as (Rhipicephalus sanguineus), is less common in Kentucky, fenoxycarb (e.g., Basis House & Kennel Aerosol or Torus(R)).
but can be a serious pest inside homes.
Fleas can be successfully controlled using the techniques American Dog Tick — Adult American dog ticks are
described above. Homeowners who lack the time to control fleas brown and about the size of a small pencil eraser. They have a themselves or who are uncomfortable applying pesticides may silvery-grey, shield-like plate covering part or all of their backs.
wish to enlist the services of a professional pest control firm.
Adult females that have filled themselves with blood are slate- Ticks are small, insect-like animals that are commonly found in woodland, mixed shrub, and overgrown areas. Withtwo body regions and eight legs, ticks are more closely re-lated to spiders than insects. They are usually reddish brownto brown, and their bodies are oval and flattened. Ticks havefour life stages: egg, larva, nymph, and adult (Fig. 2-3). Thelatter three stages feed solely on the blood of mammals, birds,reptiles, or amphibians. Some ticks feed exclusively on a single Fig. 2-4—(Left to right): American dog tick, lone star tick, andbrown dog tick. The first two species are most common in Kentucky. grey and about the size of a raisin. Larvae and nymphs aremuch smaller and more difficult to identify; they feed almostexclusively on small wild rodents. Consequently, only thereadily distinguishable adults are found on humans and pets.
Dogs are the preferred host, but these ticks also will feed oncattle, horses, and people.
The American dog tick is the principal vector of Rocky Mountain spotted fever (RMSF). It can also transmit tulare-mia and cause tick paralysis. Campers, hikers, and hunters arelikely to encounter this tick in overgrown areas, woods, fields,and parks. Pet owners also frequently find this tick on theirdogs, especially around the head and ears. The adult ticks areactive in Kentucky from spring through mid-summer.
Fig. 2-3—The life cycle of a tick Lone Star Tick—The lone star tick gets its name from a
distinct white spot on the back of the adult female. Adult host. Other species need two or more different animal hosts to males do not have this spot; instead, they have pale, lacy complete their development.
white markings on the rear edge of the back.
Adult ticks usually mate on the body of the host animal.
Lone star ticks are most prevalent in western and south- central Kentucky, but are spreading to other areas. They are usually appears between three and 30 days after the tick bite, especially abundant during spring and summer. The life cycle but develops in only about 60-70 percent of infected individu- is similar to that of the American dog tick with one notable als. Also, the rash frequently disappears within a few weeks exception: immature lone star ticks (larvae and nymphs) readily and may be overlooked.
attack humans, whereas immature American dog ticks do not.
Persons who experience any of the above-mentioned Consequently, if you are bitten by tiny larval ticks (about the symptoms after being bitten by a tick — or after spending size of the period at the end of this sentence), or slightly larger time in an area where ticks are abundant — should consult a nymphs, they are probably lone star ticks.
physician immediately. In the earliest stages, Lyme disease Lone star ticks are less frequent disease carriers than are can be successfully treated with antibiotics. As the disease American dog ticks, but they can transmit Rocky Mountain progresses, therapy becomes more difficult. Left untreated, spotted fever and tularemia. The major problem with lone star Lyme disease may result in chronic arthritis, heart disease, ticks, however, is that they often occur in tremendous num- and neurological disorders.
bers, especially as immatures. A person who walks through Lyme disease is most common in the Northeast, upper Mid- vegetation containing a clump of larval lone star ticks may west, and Pacific Coast states. Lyme disease is such a new dis- find hundreds of the tiny ticks crawling on him. Unattached ease in Kentucky that the mechanism of transmission is not yet larvae can be removed by bathing or showering. However, known. Neither the American dog tick nor the lone star tick (the once ticks are attached, removal is difficult, and their bite two most common ticks in the state) appear to be vectors of the can be very irritating. The attachment site can become in- disease. And, to date, none of the known vectors of the disease flamed and infected and is sometimes accompanied by a (e.g., Ixodes scapularis) have been found here. Until more is known about how Lyme disease in Kentucky is transmitted, Brown Dog Tick—Although less common in Kentucky
people should be aware of the early symptoms and should see a than the two previous species, the brown dog tick can be a physician if they suspect they may have been bitten by a tick.1 serious pest on dogs. The ticks are usually found around the Rocky Mountain Spotted Fever has not received the me-
ears, between the toes, and along the back. Unfed males and dia attention of Lyme disease, but it is potentially more seri- females are uniformly dark brown with no distinctive mark- ous. Each year about 10 to 30 cases are reported statewide.
ings or color patterns. The ticks become dark grey and bul- The primary vector of RMSF is the American dog tick, al- bous after they have fed.
though lone star ticks can also transmit the disease pathogen, A home can become heavily infested when dogs trans- a bacterium-like microorganism, Rickettsia rickettsii.
port ticks inside. Brown dog ticks seldom bite humans, but Symptoms of RMSF begin two to 12 days after tick at- can be a serious problem inside homes. Females can lay as tachment and include headache, chills, muscle aches, and a many as 5,000 eggs behind walls or under furniture or carpet- very high fever (104-106°F). The most characteristic sign of ing. Larvae, nymphs, and adults feed exclusively on dogs, RMSF is a rash that appears on about the second to fifth day which is why this tick is likely to become established in homes.
on wrists and ankles, later spreading to other parts of the Brown dog ticks can survive for more than six months in an body. When promptly diagnosed, RMSF can be successfully unengorged state hidden in cracks and crevices.
treated with antibiotics. In the absence of treatment, victimsmay die.
TICKS AND DISEASE
In the case of RMSF and Lyme disease, infected ticks must Ticks can transmit several serious diseases to humans, be attached for at least 12 to 24 hours for pathogens to be trans- pets, and farm animals. The two tick-borne diseases that are mitted. A person cannot become infected simply by having a tick most often reported in this area are Lyme disease and Rocky crawl over the skin or clothing. Daily body checks for attached Mountain spotted fever.
ticks greatly reduce one's chances of becoming infected.
Lyme Disease is a potentially serious bacterial infection,
transmitted through the bite of an infected tick. The disease is REMOVING ATTACHED TICKS
named for the town of Lyme, Connecticut, where it was first Attached ticks should be removed promptly to reduce reported in 1975. The bacterium, called Borrelia burgdorferi, the chance of infection and disease transmission. The mouth- is transmitted principally by a tick called Ixodes scapularis parts of a tick are shaped like tiny barbs. Therefore, the best (=I. dammini). The disease affects humans and a wide range way to remove a tick is to grasp it with tweezers as close to the of animals including pets and livestock.
skin as possible and pull it straight out with gentle, even Lyme disease manifests itself in many ways and if left pressure (Fig. 2-5). Don't jerk or twist the tick because the untreated may progress through several stages. The disease head and mouthparts may remain embedded, increasing the is difficult to diagnose clinically because early symptoms mimic chance of infection. If tweezers are unavailable, grasp the tick the flu (e.g., fatigue, headache, fever, or swollen glands, pain with a piece of tissue, trying not to squeeze or crush the tick's or stiffness in the neck, muscles, or joints). The most defini- body as this may force disease organisms into the wound.
tive early sign is a gradually expanding circular or oval-shaped Petroleum jelly, hot matches, and other "folk" methods of re- red rash (erythema migrans) at the site of the bite. The rash moval should be avoided.
1In certain areas of the state there is confusion regarding the term "deer tick". "Deer tick" is a term often used when referring to Ixodes scapularis, the principal vector of Lymedisease in the northeastern U.S. The same term is used when referring to nymphal lone star ticks which are commonly found in western and southern parts of Kentucky. The lonestar tick is not considered to be a vector of Lyme disease, although it can transmit Rocky Mountain spotted fever.
and pyrethrins. Pet owners should be advised to consult withtheir veterinarian for appropriate products to use on their pet.
Pet pens and runs also can be sprayed to control ticks that may be present in those areas. Products labeled for tickcontrol outdoors are usually labeled for use in these areas aswell. Do not contaminate food or water.
CONTROLLING TICKS OUTDOORS
Ticks are sometimes a problem in yards, especially when pets are kept outdoors. Ticks also can be a serious problem inparks, camps, picnic sites, and other recreational areas. A goodway to determine if ticks are present is to drag a 3-ft x 3-ftwhite flannel cloth through suspected areas. Ticks will attachand be visible against the white background.
Tick populations can be reduced in these areas by mow- ing and trimming lawns and other vegetation, thus creating a Fig. 2-5—To remove an embedded tick, grasp it close to the skin, less favorable habitat for ticks and their wild hosts. Wood, and pull slowly and straight out. brush piles, and other accumulated debris should also be re- Once the tick is removed, wash the affected area and your hands with soap and water, apply antiseptic, and cover with Insecticide sprays are most effective when directed into an adhesive bandage. Itching can be relieved by applying areas where ticks and their animal hosts are likely to frequent.
topical ointments such as those containing hydrocortisone.
Pay particular attention to borders and fences between wooded Keep the tick. Place it in a container with alcohol for at least or brushy areas and the lawn, around ornamental plantings, three weeks. Should any disease-related symptoms appear, beside foot paths, and the dog house. Products containing the identity of the tick may help the physician with diagnosis.
carbaryl (Sevin), chlorpyrifos (Dursban), and diazinon are ef- The Entomology Department at the University of Kentucky fective, as are permethrin, cyfluthrin (Tempo), and other syn- will identify ticks at no charge. Specimens should be accompa- thetic pyrethroid insecticides. A single application during late nied by the date and county from which the tick was collected.
April or May is often all that is required, although treatmentmay need to be repeated in June.
AVOIDING TICK BITES
The ground and vegetation up to a height of about three The best way to avoid tick bites is to follow these precau- feet should be thoroughly wetted with the insecticide. The insecticide should be applied according to label instructions.
1. Avoid walking through uncut fields, brush, and other over-
Children and pets should be kept off treated areas until the grown areas, especially from April through July. Walk in the vegetation is completely dry. Treating the entire lawn is of center of mowed trails to avoid brushing up against vegetation. little benefit since ticks avoid direct sunlight and normally will 2. When hiking or camping in tick-infested areas, wear light-
not infest areas that are well maintained.
colored clothing and long pants tucked into boots or socks. CONTROLLING TICKS INDOORS
Ticks will be easier to spot, and it will be more difficult forthem to attach to your skin. Tick control indoors is seldom required in Kentucky. This is because the American dog tick and lone star tick are rarely 3. Consider applying insect (tick) repellent to shoes, cuffs,
found indoors except on the pet. Indoor treatment is neces- socks, and pant legs. Products containing diethyl toluamide sary only for the brown dog tick, which is relatively rare in (DEET) or permethrin are most effective, but be sure to read Kentucky. Controlling this tick is difficult because of its many and follow directions for use on the container. possible hiding places inside the home. After feeding, brown 4. Regularly inspect family and pets carefully after they have
dog ticks drop off the dog and conceal themselves in cracks been in tick-infested areas. Promptly remove any ticks. Show- and crevices, where they can survive without another blood ering or bathing effectively removes ticks that have not yet meal for several months.
Management of the brown dog tick in homes requires frequent inspection and removal of ticks from pets. Pet bed- CONTROLLING TICKS ON PETS
ding should be laundered, and rugs, floors, and furniture Free-roaming pets are much more likely to become in- should be routinely vacuumed, especially along baseboards fested than are pets that are confined. Fencing in yards pre- and under and behind furniture.
vents pets from picking up ticks from surrounding areas. Fenc- Insecticides are almost always required to kill ticks hid- ing also discourages dogs and other large animals from in- den in protected areas. Treatment should focus on cracks and troducing ticks onto the property. Ticks on pets can be controlled crevices along baseboards and molding, around door and win- using sprays, dips, dusts, and insecticide-impregnated collars.
dow frames, underneath furniture, beneath the edges of car- A variety of brand names are available containing active peting, behind loose wallpaper, and in similar areas where ingredients such as permethrin, chlorpyrifos, propoxur, carbaryl, ticks might conceal themselves. Pay particular attention to areas where the dog spends time. Ticks tend to crawl up wallsand other vertical surfaces, so it will be necessary to treatcracks and crevices up high as well as low.
Effective active ingredients for indoor application include carbaryl, chlorpyrifos, bendiocarb, and permethrin.
Homeowners should be reminded to follow label directionsand always keep children and pets off treated surfaces untilthe spray has dried. Because the eggs and immatures maytake several weeks to hatch or molt, retreatment may be nec-essary to eliminate all ticks emerging from hidden areas.
Lice are parasites of warm-blooded animals, including man.
The three species of lice that parasitize humans are the headlouse, body louse, and pubic louse (Fig. 2-6). All three suckblood and cause considerable itching when they feed or crawlon the body. The body louse is also important in the transmis-sion of human diseases, most notably epidemic typhus. Mil-lions of people throughout time have died from louse borne Fig. 2-7—Life stages of the head louse. Actual size of adults is 1/16 - typhus, although in the United States, the disease has not 1/18-inch. Eggs are attached to hair shaft, whereas dandruff can been present for many years. Pediculosis is a skin condition be flicked off. resulting from continuous and severe infestation of lice.
Scarred, hardened, and pigmented skin results from continu- ANAGEMENT AND PREVENTION
ous scratching of louse bites. All three kinds of human lice The public health professional should be able to detect the can cause pediculosis.
presence of lice, and recommend steps for deinfestation andprevention. This is particularly important in the case of headlice, which infest an estimated ten percent of elementary schoolchildren each year. Specific recommendations for dealing withhead lice are discussed below. (Most of the recommendationsare also relevant to the management of body and crab lice).
As mentioned, head lice usually infest only the head, preferring the nape of the neck and the area behind the ears.
Head lice are especially common on schoolchildren betweenthe ages of three and ten. Schools bring large numbers ofchildren together in close personal contact. Hats and coatsare often shared or hung together in the same closet, permit-ting transfer of lice from one child to another. Transfer of head Fig. 2-6—Lice commonly found on humans lice can also occur by using infested combs and brushes, orresting one's head on upholstered furniture or pillows recently Lice associated with humans spend virtually their entire used by an infested person.
life on the host. Head lice are the type of louse most often The first indication of head lice is itching and scratching encountered and almost always occur on the head. Head lice caused by the bloodsucking habits of the louse. Examination are small (1/12 inch or about the size of a sesame seed), and of the hair and scalp will usually reveal the crawling forms white or grayish. They move quickly and avoid light, some- (nymphs and adults) and yellowish white eggs (nits) attached times making them difficult to see. Diagnosis is more often to the hair shafts close to the scalp. Usually all lifestages can made by the presence of the nits (eggs). Nits are tiny, yellow-
be seen with the naked eye, although a flashlight and hand ish white oval eggs attached directly to the hairs of the scalp.
lens are helpful. Red bite marks or scratch marks are often They are often mistaken for dandruff or residues of shampoo, seen on the scalp or neck.
but will not wash off or blow away (Fig. 2-7). Body lice re- There are four (4) key steps to eliminating head lice and semble head lice, but prefer to live in clothing except when preventing their return: they crawl onto the body to feed. Outbreaks of body lice are 1. The child or infected person(s) should be treated with a
usually associated with large numbers of people living in close medicated shampoo formulated specifically to control lice. quarters under poor sanitation. Transfer of body lice can oc- Several different products, most containing pyrethrins, are cur from shared bedding or clothing. Pubic (crab) lice usually available through pharmacists and physicians. Follow the infest the pubic area, but also may be found on other hairy directions on the package. Some products require retreatment areas of the body. Transfer of crab lice between individuals in 7-10 days. If one family member is found to be infested, all usually requires intimate personal contact because the lice others should be examined. Only those showing evidence of cannot survive longer than 24 hours off the host.
lice should be treated. All infested family members should be treated at the same time to prevent reinfestation from one Chiggers are the larvae of a family of mites that are some- person to another. times called red bugs. The adults are large red mites often 2. Remove all nits using a fine-tooth louse comb. Louse con-
seen running over pavement and lawns. Chiggers are extremely trol shampoos often do not kill all the nits, and surviving small (0.5 mm) and are difficult to see without magnification.
eggs will hatch within 7-10 days, continuing the cycle of The six-legged larvae are hairy and yellow-orange or light red.
reinfestation. Dead nits also tend to remain attached to the They are usually encountered outdoors in low, damp places hair, causing uncertainty about reinfestation. Nits are most where vegetation is rank and grass and weeds are overgrown.
easily removed by combing while the hair is slightly damp. Some species also infest drier areas, however, making it diffi- They can also be picked out with fingernails, or cut out with cult to predict where an infestation will occur.
a small safety scissors. Chiggers overwinter as adults in the soil, becoming 3. All personal articles that have been in contact with the
active in the spring. Eggs are laid on the soil. After hatch- infected individual should be deloused. Normal laundering ing, the larvae crawl about until they locate and attach to a with hot, soapy water (125 degrees F for 10 minutes) or dry suitable host. The larvae do not burrow into the skin, but cleaning will kill lice and nits on clothing, bed linens, and inject a salivary fluid which produces a hardened, raised towels. Combs and brushes should be soaked for 10 minutes area around them. Body fluids from the host are withdrawn in a pan of very hot water. (Note: steps 1-3 should be per- through a feeding tube. Larvae feed for about 4 days and formed at the same time to avoid reinfestation after sham- then drop off and molt to nonparasitic nymphs and adults.
Chiggers feed on a variety of wild and domestic animals, aswell as humans. The life cycle (from egg to egg) is com- 4. To reduce the chance of reinfestation, children should be
pleted in about 50 days.
instructed not to share hats, clothing, or brushes with their Most people react to chigger bites by developing red- classmates. Each child should have a separate storage space dish welts within 24 hours. Intense itching accompanies the for hats and other clothing at home and school to prevent welts, which may persist for a week or longer if not treated.
contact with other garments. If this is not possible, coats Bites commonly occur around the ankles, waistline, armpits, should be hung on hooks so they do not touch, or on the or other areas where clothing fits tightly against the skin.
backs of students' chairs. Besides causing intense itching, chigger bites that are Elimination of a head lice outbreak in a school, nursing scratched may result in infection and sometimes fever. Chig- home, or similar shared facility requires prompt, coordinated gers in North America are not known to transmit disease.
action and administrative support to prevent the spread of Persons walking in chigger-infested areas can be pro- lice to uninfected individuals. Unless all affected persons are
tected by treating clothing (cuffs, socks, waistline, sleeves) treated, the condition will continue.
or exposed skin with tick repellents. Some repellents should Treatment of the premises or clothing with insecticides
only be used on clothing; and it is important to follow label is generally not required or recommended for the control
directions. People who suspect they may have been attacked and prevention of head, body, or crab lice. This is because the
by chiggers should take a soapy bath immediately and apply lice cannot survive for any length of time off of their human
antiseptic to any welts. A local anesthetic will provide tempo- rary relief from itching. Regular mowing and removal of weeds and brush make areas less suitable for chiggers and their wildhosts. Mowing also enhances penetration and performance Mites (Fig. 2-8) are very small arthropods that are closely of miticides, should they be required. Chigger populations related to ticks. Mite larvae have six legs whereas the nymphal can be further reduced by treating infested areas with residual and adult stages have eight. Most species of mites are pests miticides. Applications should be thorough but restricted to of agricultural crops. However, certain types of mites are para- areas frequented and suspected of being infested.
sitic on humans.
Chiggers
The sarcoptic itch mites, Sarcoptes scabei, infest the skin of a variety of animals including humans. The types of Sar-coptes inhabiting the skin of mammals are considered formsof Sarcoptes scabei and can exchange hosts to some degree.
(For example, Canine scabies can be temporarily transferredfrom dogs to humans, causing itching and lesions on thewaist, chest, and forearms.) Human scabies mites are very small and are rarely seen.
They commonly attack the thin skin between the fingers, the bend of the elbow and knee, the penis, breasts, and the shoul-der blades. The mites burrow into the skin, making tunnelsup to 3 mm (0.1 inch) long. When they first burrow into the Fig. 2-8—Mites parasitic on humans: (a) chigger, (b) scabies mite, skin, the mites cause little irritation, but after about a month, and (c) bird mite. sensitization begins. A rash appears in the area of the burrows and intense itching is experienced.
can be used in conjunction with residual sprays. Space treat- Scabies mites are transmitted by intimate personal con- ments are especially useful when the mite infestation has dis- tact, usually from sleeping in the same bed. The adult fertil- persed widely from the nesting site. In this case, more ex- ized female mite is usually the infective life stage. She adheres tensive treatment with residual and non-residual insecti- to the skin using suckers on her legs and burrows into the skin cides may also be necessary in other areas of the structure where she lays her oval eggs. In 3 to 5 days these eggs hatch into where mites are observed. A vacuum cleaner or cloth moist- larvae and move freely over the skin. Soon they transform into ened with alcohol can be used to eliminate mites crawling nymphs and reach maturity 10 to 14 days after hatching.
on open surfaces.
A scabies infestation should be handled as a medical problem and is readily diagnosed and treated by most physi- cians. The first step to control a scabies infestation usually There are several species of bed bugs, all of which are involves softening the skin with soap and water to make sure parasites of warm-blooded animals. The common bed bug,
the pesticide treatments can penetrate well. An evening bath whose preferred host is humans, is rarely encountered, pre- followed by overnight treatment works best. A total body sumably because of improvements in sanitation. Related spe- (neck-down) application of topical pesticide medication should cies, such as the bat bug and bird bug, prefer to feed on bats,
remain for 8-12 hours before showering in the morning. Com- birds, and other wild hosts, but will also feed on humans if the monly used products include lindane (Kwell®), permethrin opportunity arises or the preferred host dies or leaves the (Elimite®), and crotamiton (Eurax®).
roost. Adult bed bugs are about 1/4-inch long and reddish Because the symptoms of scabies mite infestations are brown, with oval, flattened bodies (Fig. 2-9). Bed bugs prefer delayed by about a month, other members of the household to hide in cracks and crevices during the daytime and come besides those showing symptoms may be harboring the mites.
out to feed on the host's blood at night, usually while the host It is important that everyone in the infected family or living is sleeping. Infestations are usually detected by the welts and group go through the treatment regime. A second treatment irritation caused by the bites, and the fecal smears and blood may be necessary to eliminate an infestation of scabies mites, spots visible on pillowcases, sheets and mattresses. Heavy in- but patients should avoid overzealous pesticide treatment festations of bed bugs are also accompanied by a distinct odor.
because itching may persist for a week or more after treatment The key to controlling bed, bird, and bat bugs is to locate and does not necessarily indicate treatment failure.
Scabies mites cannot live off of a human host for more than 24 hours. Therefore, insecticide treatment of premises isnot warranted. It is recommended, however, that coincidentwith treatment, the clothing and bedding from infested indi-viduals be washed in hot water or dry cleaned.
Bird and Rodent Mites
Parasitic mites that occasionally infest buildings are usu- ally associated with wild or domestic birds or rodents. Birdand rodent mites normally live on the host or in their nests, but Fig. 2-9—Bed bug migrate to other areas of the structure when the animal dies orabandons the nest. Rodent mites often become a nuisance after and treat all cracks and crevices where the bugs may be hid- an infestation of mice or rats has been eliminated. People usually ing. Typical hiding places are in the tufts, folds and seams of become aware of the problem when they are attacked by mites mattresses, and cracks in the box spring and bed frame. Heavier searching for an alternate food source. Their bites cause moder- infestations often spread to behind baseboards, window and ate to intense itching and irritation. Rodent and bird mites are door casings, behind pictures, electrical switch plates, and very tiny, but usually can be seen with the naked eye. They are loose wallpaper, in the pleats of drapes, and the upholstery of about the size of the period at the end of this sentence.
furniture. When inspecting for bed bugs, look for the insects The first step in controlling bird or rodent mites is to themselves as well as the telltale fecal and blood spots indicating eliminate the host animals and remove their nesting sites. Of- that a hiding place is nearby. Residual insecticides (sprays or ten, the nests will be found in the attic, around the eaves and dusts) used to control cockroaches and ants are usually effec- rafters, or in the gutters or chimney. Gloves should be used tive, but always consult the label for specific instructions.
when handling dead animals. A respirator should also be worn Following thorough inspection/treatment of living ar- when removing nest materials to avoid inhaling fungal spores eas, efforts should be made to locate and eliminate poten- and other potential disease-producing organisms associated tial wild animal sources of infestation. These may include with the droppings.
birds, bats, or squirrels in the attic, or possibly mice or rats.
After nests are removed, the areas adjacent to the nest If bat bugs or bird bugs are found in these areas, residual should be sprayed or dusted with a residual insecticide such and non-residual insecticides should be applied, and the as those products labeled for flea control. Space or ULV treat- wild hosts excluded.
ments with non-residual materials (e.g., synergized pyrethrins) toes are often confused with midges, punkies, biting gnats,and other flies.
Mosquitoes have done more harm to human health Eggs—Mosquito eggs, elongate and about 1/40-inch long,
and well-being than any other insect group. They are the turn dark brown or black when ready to hatch. Eggs are laid only natural carriers of such debilitating diseases as ma-laria, yellow fever, dengue, and several types of viral en-cephalitis. Mosquitoes can also transmit filarial diseases(caused by parasitic worms) to humans and animals. Theviral encephalitides and dog heartworm are the only dis-eases that are a threat in Kentucky. The mosquito's annoyingbiting habits often make it a nuisance around the home, and inparks and other recreational areas. Fortunately, most mos-quito species feed on animals other than humans. However,some of these species can be pests of pets and farm animals.
Kentucky has over 50 mosquito species. Only the female mosquito bites; males feed strictly on nectar and other plantjuices. Female mosquitoes need an additional source of pro-tein (in the form of a blood meal) before they can developeggs. Females also feed on nectar and plant juices, using thisfood source for flight and metabolism.
Biology and Habits
Mosquito development consists of four stages: egg, larva, pupa, and adult (Fig. 3-1). All life stages except the adult areaquatic. Mosquitoes are generally small (less than 1/2-in) andfragile. Their most obvious characteristics include one pair ofwings with scales on the wing veins and hind margin, and anelongated beak with piercing mouthparts (Fig. 3-2). Mosqui- Fig. 3-2—A mosquito adult singly or in batches of 50-400. Anopheles and Aedes depositeggs singly, Culiseta and Culex spp. deposit them in rafts.
Oviposition by most groups is on the surface or along themargins of quiet pools of water. However, flood water and saltmarsh mosquitoes, as well as many tree-hole breeders, (e.g., Aedesand Psorophora) oviposit above the waterline in sites subject toflooding by tidal water, overflow, or rainwater. Each mosquitospecies lays its eggs in a specific type of site.
Eggs laid by floodwater mosquitoes do not all hatch at the same time. Most hatch after the first flooding, the remain-der will emerge only after the second or subsequent floodings.
Eggs of some common Aedes species will hatch only after 4years of intermittent flooding.
Larvae—Mosquito larvae are commonly known as "wig-
glers," because of their swimming habits. They differ fromother aquatic insects by an absence of legs and by their bul-bous thorax, which is wider than the head or abdomen. Incontrast to other fly larvae, most larval mosquitoes have acomplete head capsule and a prominent breathing tube lo-cated on the eighth abdominal segment (Fig. 3-3). This stagelasts about 7 days, depending on temperature.
Mosquito larvae can breed in virtually any naturally oc- curring collection of water. Great swarms may be producedfrom either fresh or brackish water, polluted or clear. Breedingsources may include water in tin cans, vehicle tires, hoof prints,tree holes, leaf cups, or the margins of rivers, streams, lakes, Fig. 3-1—Anopheles, Aedes, and Culex mosquitoes at various stages or impoundments. Mosquitoes cannot breed, however, in large of development bodies of water with clean edges because the larvae are microorganisms growing on solid surfaces. Some mosquitoes,including Toxorhynchites and Psorophora species, are con-sidered beneficial insects because the larval stage activelypreys upon other mosquito larvae.
Pupae—Mosquito larvae molt 4 times. The last results
in a non-feeding pupa or "tumbler." The pupal stage isquite short, usually 2-3 days. The pupa is shaped like acomma (Fig. 3-5). The "dot" part of the comma is called thecephalothorax and the "tail" of the comma is the abdomen.
A pair of breathing "trumpets" are situated on top of thecephalothorax and paddle-like flaps on the end of the ab-domen. The pupa is remarkably active and sensitive to dis-turbances. When alerted, it quickly darts in a tumbling ac-tion to deeper water and, after a few moments, rises withlittle motion back to the surface. Pupae are aquatic, butthey can survive quite well on a moist substrate such aswet mud in a drying puddle.
Adult—The adult mosquito emerges from the pupal case
onto the surface of the water. Careful movements by the emerg- Fig. 3-3—Dorsal view of a Culex mosquito larva unable to withstand wave action.
Most wigglers hang suspended diagonally from the wa- ter surface by means of the breathing tube. Anopheles larvaedo not have a tube, however, and lie horizontally just beneaththe surface of the water by means of float hairs (Fig. 3-4).
Mosquito larvae are quite mobile and will quickly dive to thebottom if disturbed. They will return to the surface shortly.
Most mosquito larvae feed by filtering out microorgan- isms and other particulates in the water, or by "browsing" Fig. 3-5—A mosquito pupa ing adult are required to ensure that it does not fall sidewaysand become trapped in the surface film.
Male mosquitoes usually live no longer than 1 to 2 weeks.
Females with ample food may live for several months although,during the summer, female survival may average closer to twoweeks. Some mosquito species have only one generation eachyear. Other species may have four or more generations peryear, with populations building up to large numbers by latesummer.
Some species can fly no more than a few city blocks, whereas others can travel up to twenty miles. Most mosqui-toes are active only at night, although some varieties biteduring the daytime. When they are not active, adult mosqui-toes tend to seek protection in quiet areas with high humidity.
Resting sites for adult mosquitoes include shrubs, woodedareas, and similar dense vegetation, drainage ditches, sewers,or under the eaves of buildings.
Fig. 3-4—Dorsal view of an Anopheles mosquito larva Mosquito Species Common in Kentucky
Anopheles quadrimaculatus. These large, dark-brown
Only trained specialists can differentiate between mos- mosquitoes have four dark spots near the center of each wing; quito species. Knowing which species is involved is crucial the legs are entirely dark. Eggs are laid singly on the water to planning appropriate control measures. The following are surface with lateral floats to keep them suspended. One hun- some of the most troublesome species found in Kentucky.
dred or more eggs are laid at a time. This species is the most Aedes albopictus, the Asian tiger mosquito, was first dis-
important vector of malaria in the eastern U.S. and can be covered in 1985 in the Houston, Texas, area in used tires im- found frequently in houses. Their bites are less painful than ported from Japan. It has spread rapidly throughout the east- many other mosquitoes and often go unnoticed. Breeding ern U.S. where it is now reported in 25 states. The Asian tiger sites are chiefly in permanent, freshwater pools, ponds, and mosquito has the potential to become established through- swamps that contain aquatic vegetation or floating debris.
out much of the U.S. because it can survive winter tempera- City park ponds, sluggish streams, and shallow margins of tures. As of 1994, 46 counties in Kentucky were infested with the reservoirs and lakes can contain many larvae. During the day mosquito, causing concern among state health officials. It is an adults rest in cool, damp, dark shelters such as buildings, caves, aggressive daytime biter and has the potential to transmit numer- and under bridges. These mosquitoes feed at night and will readily ous diseases including dengue, yellow fever, La Crosse encepha- enter houses to feed on humans. Cows, horses, mules, pigs, and litis, eastern equine encephalitis, and dog heartworm. La Crosse chickens are also attacked. Adults usually remain within one-half encephalitis, eastern equine encephalitis, and dog heartworm are mile of their breeding site. Breeding occurs throughout the sum- of particular concern to Kentuckians because the pathogenic mer months. Adult fertilized females are the overwintering stage.
agents responsible for these diseases are known to occur here.
Culex pipiens, the common house mosquito, is brown,
The Asian tiger mosquito is of average size, black and of medium size and has cross bands of white scales on the white, with banded white legs and a distinctive single white abdominal segments, but is without prominent markings. It is band down the length of the back of the thorax. One of the a vector of St. Louis encephalitis and dog heartworm. Breed- major breeding sites for the mosquito is artificial containers, prin- ing occurs in rain barrels, tin cans, tires, storm-sewer catch cipally vehicle tires. The movement and improper storage of used basins, street gutters, polluted ground pools, cesspools, open tires is the primary means of dispersal in this country.
septic tanks, etc. Eggs are laid on the water surface as rafts in Aedes canadensis is a dark mosquito with the ends of the
clusters of 100-400. The flight range is restricted unless great legs banded with white. It is a serious pest in woodlands. This numbers are produced. Adults are active only at night and can be species overwinters in the egg stage and is one of the first found resting during the day in and around houses, out-build- mosquitoes to appear in early spring. Larvae breed in wood- ings, and various shelters near their breeding places. They com- land pools filled by melting snow or spring rains. It prefers monly enter houses. This mosquito overwinters as an adult.
pools with bottoms containing dead and decaying leaves,although it is sometimes found in roadside puddles, sink holes, Mosquitoes and Disease
wooded swamps, etc. Eggs are laid singly on the ground above Mosquitoes are not naturally infected with disease agents; the waterline in woodland pools. Eggs are able to survive they must first acquire these pathogens from a "sick" indi- long periods of drying. Biting occurs most frequently during vidual or host before they can be passed to a "healthy" one.
the evening hours, but can occur during the day or night.
For example, just because a person was bitten by Anopheles This mosquito is a secondary vector of La Crosse encephalitis.
quadrimaculatus (the mosquito capable of transmitting ma- Aedes triseriatus, the eastern tree hole mosquito, is black
laria in Kentucky) doesn't mean that he or she will contract with silvery-white scales at the sides of the thorax. There are malaria. For that to happen, the mosquito would first have had no bands on the legs. This mosquito breeds in tree holes, to have bitten an individual suffering from malaria -- a highly tires, and other artificial containers. The bites are painful and unlikely event in Kentucky.
can be annoying. This mosquito does not fly far from its breed- The following mosquito-borne diseases are of some concern ing place and is the principal vector of La Crosse encephalitis in Kentucky. in Kentucky. It has several generations per year and overwin- St. Louis Encephalitis (SLE) is one of the most common
ters in the egg stage.
arthropod-borne viruses (arboviruses) in the U.S. In nature, it Aedes vexans, the inland floodwater mosquito, is a me-
is maintained and transmitted among birds, primarily by Culex dium-sized brown mosquito with narrow rings of white scales mosquitoes. Humans can become ill when bitten by an in- on the hind tarsi and a "V"-shaped notch at the middle of each fected mosquito. Infected individuals may experience abrupt band of white scales on the upper surface of the abdomen.
onset of fever, nausea, vomiting, and severe headaches. These Common breeding sites are rain pools, floodwaters, roadside symptoms usually develop within 5 to 7 days after someone is puddles, and just about all temporary bodies of freshwater.
bitten. People of any age may contract the disease; however, The eggs are laid on the ground above the waterline and disease incidence is greater and symptoms more severe in hatch when flooding occurs. Adults can fly long distances people 60 years or older. Mortality rates range from 2 to 20 from their breeding sites with flights of ten miles being com- percent, with the highest mortality occurring in the oldest age mon. Adults are vicious biters and are especially annoying at dusk and after dark. They rest during the day in grass and Humans become infected with SLE only as a result of other vegetation. This mosquito overwinters in the egg stage.
being bitten by a mosquito that had formerly contracted the It is a secondary vector of eastern equine encephalitis.
pathogen from biting an infected bird. There is no person-to- person transmission via mosquitoes, because the virus con- lations with mosquitoes and HIV show that a mosquito feed- centration (titer) in human blood never reaches a sufficient ing on an HIV carrier circulating 1000 units of HIV has a one
level to render a biting mosquito infective. Thus, humans are in 10 million chance of injecting a single unit of HIV to an considered to be an "accidental" or "dead end" host for this AIDS-free recipient. In other words, an AIDS-free individual disease. Disease outbreaks are most likely to occur from mid- would have to be bitten by about 10 million mosquitoes that summer through early fall when Culex populations are at their peak.
had previously fed on an AIDS carrier to receive a single unit Eastern Equine Encephalitis (EEE) is an infection main-
of HIV from contaminated mosquito mouthparts! Using the tained in nature by a bird-mosquito-bird cycle similar to SLE.
same calculations, crushing a fully engorged mosquito con- Horses are involved as dead end hosts in the cycle, as are taining AIDS-infected blood would still not begin to approach humans. This virus can infect persons of any age, but young the levels needed to initiate infection. In short, mechanical children and infants are most susceptible. Mortality in hu- transmission of AIDS by HIV-contaminated mosquitoes ap- mans may exceed 50% and can be significantly higher in horses.
pears to be well beyond the limits of probability.
Children and infants who survive the infection are frequently What about contaminated blood inside a mosquito's afflicted with varying degrees of mental retardation and pa- mouthparts? Many people think of mosquitoes as tiny, flying ralysis. A number of mosquitoes, including Culiseta melanura hypodermic syringes—and if hypodermic syringes can suc- and several Aedes species, are capable of transmitting this cessfully transmit HIV from one individual to another, then mosquitoes should also. However, unlike a syringe, the mos- La Crosse Encephalitis (LAC)—The natural cycle of LAC
quito delivers its salivary fluids through one passage (i.e., differs from the other encephalitides in that the natural hosts tube) and draws blood up another. As a result, the food canal is are small animals such as rabbits, hares, and squirrels, rather not flushed out like a used needle, and blood flow in mosquito than birds. The primary vector is the eastern tree hole mos- feeding is always one-way. Thus, the mechanics involved in quito, Aedes triseriatus. Humans are susceptible to this dis- mosquito feeding are totally unlike the mechanisms employed by ease but mortality is usually low.
syringes (and far less likely to result in transmission of HIV).
Dog Heartworm is caused by the filarial worm Dirofi-
laria immitis. It is a serious disease for all breeds of dogs in Kentucky. Several mosquito species can transmit this para- An effective mosquito management program cannot be site, including Culex pipiens and several Aedes species. Mos- planned or implemented until surveys are made to determine quitoes ingest the immature worms, called microfilariae, while which species are present, their relative abundance, and the taking blood from infected dogs. After several days, the fully location of potential breeding sites. Moreover, understand- developed heartworm larvae are transmitted via the mosquito's ing the biology of the species involved is essential so that mouthparts to a healthy dog when the mosquito feeds again.
control efforts are not only directed at the proper habitat, but The larvae grow and eventually migrate to the right ventricle of at the right time. Surveys can be labor intensive but will allow the dog's heart where they mature and reproduce. The adult personnel to focus control efforts on only those species that female worm can grow to approximately 11 inches and the male 6 are causing a problem. This helps mosquito control personnel inches. Large numbers of adult worms can develop in the host avoid unnecessary intrusion into areas which do not need to dog, usually killing the infected animal.
be treated, thus saving time and money.
Surveys for eggs and oviposition sites can often be a useful
Mosquitoes and AIDS
predictor of mosquito abundance. Mosquito egg surveys for News releases concerning the possibility of mosquitoes bio- floodwater mosquitoes are often used to schedule an effective logically or mechanically transmitting AIDS (Acquired Immune pre-hatch application of insecticide. Oviposition traps constructed Deficiency Syndrome) were common when the disease was first with a black-painted jar or open can, a wooden paddle serving as recognized, and the subject is still addressed by tabloids that the oviposition site, and a little water in the trap, have proven seek headlines to increase their circulation. The National Cen- valuable in sampling for Aedes albopictus and Aedes triseriatus.
ters for Disease Control (CDC) has conducted several scientific However, surveys for egg rafts of Culex, and single floating eggs studies on this topic and all of these clearly show that mosqui-
of Anopheles, are too difficult to be useful.
toes cannot transmit AIDS. There are several reasons for this:
While egg surveys are often useful, larval surveys are
Human immuno-deficiency virus (HIV) is ingested by the primary means of deciding whether control measures mosquitoes along with the blood meal. However, mosquitoes should be applied to aquatic sites. A white dipper equipped ingesting HIV-infected blood digest the entire blood meal with a long handle is the collecting tool most often used (Fig.
within 1-2 days, completely destroying any virus particles
3-6). Brown larvae can be easily seen on a white utensil. Some that could potentially produce infection.
"stealth" is required when dipping for mosquito larvae be- What about the possibility of mosquitoes "mechanically" cause the larvae quickly swim to deeper water when disturbed.
transmitting HIV on the outside of the mouthparts? In order The surveyor must also not overlook obscure larval sites, for insect-borne viruses to be passed from one individual to such as cattle hoofprints in wet pastures or on the edges of the next (via contaminated blood on the mouthparts), the water holes and ponds. For examining tree holes, artificial pathogen must be present at very high levels in the infected containers, and similarly inaccessible cavities, a large-capac- individual's bloodstream. Infected humans rarely circulate ity rubber suction bulb and flexible extension tube can be more than 10 units of HIV virus particles in their blood. Calcu- used to draw out the water into a white metal pan.
Light traps are relatively inexpensive and are easy to set up. They are most useful in determining the presence or ab-sence of a particular mosquito species, and in demonstratingpopulation trends. However, light traps are ineffective for de-termining the absolute number of mosquitoes in an area. Lighttraps collect only those mosquitoes that are active at night andare attracted to lights. Therefore, light traps may not necessarilycollect all the mosquito species present in the area.
Another disadvantage of light traps is that they are non- selective: they collect all mosquitoes attracted to them as wellas flies, beetles, and other insects attracted to light. Many ofthe mosquitoes caught in a light trap may actually be feedingon reptiles or rodents and may be of little, if any, public healthimportance. Despite these limitations, light traps are an impor-tant surveillance tool.
Another technique used in adult mosquito surveillance is the landing/biting count. This method uses humans or ani-
mals as the attractant. The human or animal host is placed at a
specific location and remains motionless. Mosquitoes are at-
tracted to the host, and as they land to feed, they are collected
with a battery-powered aspirator. This technique is very use-
ful because only those species that bite that particular host
will be collected. This technique requires that the host be
bitten, and therefore is not recommended when there is a high
Fig. 3-6—Mosquito monitoring equipment. The most important device risk of disease transmission.
is a white enamel dipper equipped with a long handle for sampling Light traps, dippers, and other mosquito surveillance equip- larvae and pupae. ment can be purchased through BioQuip Products, 17803 LaSalleAve., Gardena, CA 90248-3602 (Tel. 310-324-0620).
An important survey method for collecting adult mosqui- toes is the light trap. A variety of light traps have been de-
signed for sampling mosquitoes, one example being the New Most successful mosquito management programs con- Jersey light trap (Fig. 3-7). This trap contains an incandescent centrate on control of the larvae. This stage of the insect's life bulb, which serves as the attractant, and a fan to draw nearby cycle is concentrated in specific, identifiable areas. Larval mosquitoes into the killing chamber. A portable, battery-oper- mosquito control can be accomplished either by reducing ated modification of the New Jersey light trap has also proven breeding sites, employing biological control agents, or by applying chemical larvicides (insecticides) to breeding sitesthat cannot be eliminated.
Breeding Site Reduction
The most effective way to control mosquitoes is to find and eliminate their breeding sites. Eliminating large breedingareas such as swamps, or sluggishly moving streams or ditchesmay require community-wide effort. The initial investment isusually high, but significant savings can be realized over time.
In these operations, expert advice must be available to pre-vent potential environmental problems. For example, filling aswampy area may block normal drainage patterns, creatingnew breeding sites or interfering with aquatic life.
In addition to reducing large mosquito breeding sites, individual property owners can take the following steps to
prevent mosquito breeding on their own premises.
• Dispose of tin and soda cans, old tires, buckets, plastic
Fig. 3-7—Schematic diagram of a New Jersey light trap. sheeting, or other containers that can collect and hold wa-ter. Water should not be allowed to accumulate at the base of Carbon dioxide (a respiratory gas given off by animals) is flower pots or in pet dishes for more than 5 days. a strong attractant to mosquitoes. For this reason, dry ice is • Clean debris from rain gutters and remove standing water
often used in conjunction with light traps, resulting in signifi- under or around structures, or on flat roofs. cant increases in the number of mosquitoes caught.
• Drain childrens' wading pools when not in use (or at least
Adult Control (Adulticiding)
change the water weekly). Adult mosquito control programs are most successful if • Change the water in bird baths at least once a week.
large areas are to be treated. In general, adulticiding provides • Remove, drain, or fill tree holes and stumps with mortar.
only temporary relief by reducing populations to less annoy- • Eliminate seepage from cisterns, cesspools, and septic tanks.
ing levels. However, this may be the most practical technique • Eliminate standing water from around animal watering
for local problems or in the event of a disease outbreak. In addition, some adult mosquito species can fly long distances,often making it necessary to supplement larval control mea- • Irrigate lawns and gardens carefully to prevent water from
sures with adult control. A listing of some mosquito adulticides standing for several days. is presented in Tables 3-2 and 3-3.
• Keep the grass mowed around ponds and other bodies of
water, taking care to keep clippings out of the water.
Table 3-1. Some suggested larvicides for mosquito breeding
• Maintain farm ponds according to good management prac-
waters. (For specific application rates and safety precautions, tices. Excessive amounts of emergent aquatic vegetation will follow label directions.) shelter mosquitoes. Stagnant ponds and waste lagoons alsocan produce very large numbers of mosquitoes. Insecticide
Common name
Vectobac AS, WP & G Nematodes, planaria, microsporidia, and even other pre- israeliensis (Bti) Bactimos WP, G, P & Briquets daceous mosquitoes such as Toxorhynchites, show some promise against mosquito larvae. However, the most effective Altosid P & Briquets biological control agents to date are predaceous fish such asthe mosquito fish, Gambusia affinis, and the common guppy, Abate SG, EC & CG Poecilia reticulata. These fish are approximately 1 1/2 inches *AS=Aqueous Suspension, CG=Celatom Granule, long and feed voraciously on mosquito larvae. They are com- EC=Emulsifiable Concentrate, G=Granule, HP-D=Higher Potency- monly found in streams and creeks where they can be seined Double, P=Pellet, SG=Sand Granular, WP=Wettable Powder and transferred to sites harboring mosquito larvae. These fishcan be so effective that many county mosquito abatement Table 3-2. Some suggested ULV insecticides for adult mos-
districts in the U.S. maintain their own fish breeding programs.
quitoes. (For specific application rates and safety precau- One drawback to using this method is that some mosquito tions, follow label directions.) insecticides are lethal to the fish.
Common name
The use of insecticides is, at best, a temporary measure that should be limited to only those situations for which no Cythion LC (= Fyfanon) other alternatives exist. Chemical control can be divided into two general categories: (1) Larviciding is the most efficient
and effective method and should be the basis of any chemical piperonyl butoxide control program. (2) Adulticiding is less efficient and should
be used only for supplemental or emergency purposes. The
resmethrin pluspiperonyl butoxide detection of active transmission of mosquito-borne disease isan example of such an emergency.
*LC=Liquid Concentrate Larval Control (Larviciding)
Table 3-3. Some suggested insecticides for application as
Solving a mosquito problem by killing the larvae is the mist sprays for adult mosquitoes. (For specific rates and safety most logical approach because the mosquitoes are being con- precautions, follow label directions.) trolled before they become a nuisance. The application of larvicides should only be made at sites where mosquito larvae Common name
of the target species are present. The degree of control ob- tained with larvicide applications depends upon the amountof pollution in the water, as well as the type and amount of vegetative cover present. Where vegetative cover is heavy, Cythion EC (= Fyfanon) granular formulations frequently provide better control than emulsions or oil spays. Repeated insecticide treatments maybe needed, especially after heavy rainfall. A listing of some mosquito larvicides is presented in Table 3-1.
*EC=Emulsifiable Concentrate, MF=Mosquito Formulation,SUS=Suspension Aerial Application—Application by fixed-wing aircraft
labeled for flying insect control indoors. Aerosol space or helicopters for control of mosquitoes is a common practice.
sprays containing synergized pyrethrins often produce However, this method is generally not feasible for most areas rapid results. Doors and windows should be kept closed in Kentucky because of its high costs and potential envi- for 15-30 minutes after spraying. Only products labeled for ronmental concerns. In most cases, the insecticides labeled flying insects should be used.
for aerial application are specific formulations designed for Repellents—Repellents can protect humans from mos-
this purpose. Aerial applications are most useful under emer- quito bites for 1-12 hrs, depending on how much a person gency conditions, or when the areas to be treated are too sweats and rubs the skin, and the percentage of active ingre- large or inaccessible for treatment with vehicle-mounted dient in the repellent. Repellents are formulated and sold as aerosols, creams, and liquids. Repellents containing ingredi- Aerosol Application—Aerosols are applied to control
ents such as diethyl-meta-toluamide (DEET) or dimethyl mosquitoes outdoors using specialized equipment that dis- carbate are most commonly used. The area of skin to be pro- penses insecticides in extremely small droplets. Aerosols work tected should be covered evenly, because mosquitoes will as a contact toxicant and have no residual effect. Consequently, find and bite spots left untreated. It is often helpful to apply they are effective only as a space treatment against actively repellents on outer clothing as well as the skin because many flying adults. Aerosols are dispensed from the application mosquitoes can bite through thin, tight-fitting clothing. Do device and allowed to drift as a fog with the wind through the not apply repellents to the eyes, nostrils, or lips.
target area. This technique is effective only where there is DEET is a very effective repellent but should be used little wind. Aerosols can treat a swath of approximately 300 according to the product label. Do not apply DEET to the feet. Because the primary activity period for most pest and hands of young children. In addition, in very rare cases, use vector mosquitoes is during the evening hours, aerosol appli- of this product may cause skin reactions. If a reaction to DEET cations are usually most effective during this period.
is suspected, wash the affected area and contact the local Thermal Foggers—Thermal foggers dispense the insec-
poison control center.
ticide by heating diesel oil or water to the vapor point andreleasing the vapors along with the insecticide so that a thick Additional Control Measures
smoke or fog of very fine particles is released. This technique Vegetation Management—Many adult mosquitoes pre-
is seldom used any more in the U.S.
fer to rest on weeds and other vegetation. Trimming or elimi- Ultra Low Volume (ULV) Fogging—Special nozzle adap-
nating areas of dense vegetation will force mosquitoes to find tations and development of micrometering systems now make other, more distant, resting sites.
it possible to apply undiluted insecticides in extremely small Mechanical Barriers—Mosquitoes can be kept out of
droplets (less than 25 um on average) that can give effective buildings by keeping windows, doors, and porches tightly coverage for adult mosquito control. Such application tech- screened with 12-18 mesh screening. This method is not as niques now make it possible to reduce application volume to important in buildings that have air conditioning. Those few less than 4 fluid ounces of pesticide per acre.
insects that do get into structures can be eliminated with a fly ULV generators have several advantages over thermal fogging units. Less insecticide is applied with ULV, resulting Insect Electrocutors—Insect electrocutors (e.g., "bug
in fewer potential environmental problems. Because smaller zappers"), using ultraviolet light as an attractant, are gener- quantities of insecticide are applied, smaller holding tanks are ally ineffective at reducing outdoor populations of mosqui- needed, allowing smaller, more economical vehicles to be used.
toes or their biting activity. Light traps using ultraviolet light Finally, there is a significantly reduced hazard to traffic com- do capture large numbers of flying insects, including mosqui- pared with the near non-visibility created by thermal fog ap- toes, when used inside buildings.
Numerous other devices, including ultrasonics and mos- Mist Applications—Misting involves applying insecti-
quito-repellent plants, are available which claim to attract, repel, cides suspended in water using powerful mist blowing ma- or kill outdoor infestations of mosquitoes. These devices are chines. Mist droplets are somewhat larger than aerosol drop- generally ineffective. Individuals considering purchasing such lets and settle faster. Thus, misting does not have the "reach" devices should first consult with a mosquito specialist.
available in ULV applications. However, mists do provide someresidual control in addition to contact kill. Avoid direct appli- cation to parked cars because their finishes may become spot- All good public health programs must include commu- ted if droplets are not washed off immediately.
nity-wide education of the public to gain and maintain sup- Residual (Surface) Spraying—Residual pesticides are
port. This is especially important with mosquitoes. Wide- usually applied in water using hydraulic field or hand spray- spread aerial spraying for mosquitoes can produce anxiety ers. This type of application is of limited utility because re- and concern over the effects of pesticides on human health.
sidual effectiveness of the treatment is usually short. Residual Homeowners can be of great help by managing their own sprays are applied as surface applications to tall grasses, property to eliminate breeding sources of several mosquito shrubs, trees, buildings, playgrounds, etc.
species. The effectiveness of any area-wide public health Indoor Control—Mosquitoes found inside buildings
program can only be helped if people understand the can be killed with most household aerosol sprays that are program's benefits and limitations.
Flies are well equipped to transmit bacteria and other dis- ease-producing organisms. Most are highly mobile, and their Flies, especially in large numbers, can be very annoying bodies are covered with thousands of tiny hairs. Flies have pads and seriously interfere with work and recreational activities.
on the bottom of their feet, which aid in the mechanical pickup For centuries, flies have had a significant impact on human and transfer of pathogenic organisms. Many species, such as health and welfare because of their ability to spread disease.
the house fly, also have "sponging" mouthparts for lapping up Most fly species have evolved to feed and breed in decaying and ingesting liquid foods. As the house fly feeds, it regurgitates organic matter, including garbage, sewage, dead animals, or digestive enzymes and bacteria onto the food surface.
manure. Flies have a high potential for spreading disease or- Other species of flies, including black flies, deer flies, and ganisms because they show little preference when selecting stable flies, have piercing/sucking mouthparts designed to feeding sites. They will just as readily feed on dog droppings in suck blood. Bites of these flies are painful and may seriously the lawn as they will potato salad at a family picnic (Fig. 4-1).
interfere with outdoor activities.
All flies have four stages in their development: egg, larva, pupa, and adult. The habitat in which the adult female choosesto lay her eggs differs depending upon species (Table 4-1).
Optimum larval development requires that the breeding me-dium be moist, but not wet. Many flies of public health signifi-cance lay their eggs in moist, decaying organic matter —hu-man garbage and waste, manure of domestic animals, or de-caying vegetation, fruits, or vegetables. After the eggs hatch,the larvae (called maggots) feed upon organic material, even-tually transforming into the pupal stage from which they lateremerge as adults. The development rate varies among speciesand is greatly influenced by temperature. Under ideal condi-tions, development can be completed in as little as one week.
Considering that a single adult fly can lay several hundred Fig. 4-1—Flies often feed on filth, before alighting on human food.
eggs, the potential for a serious fly infestation is enormous.
Table 4-1: Summary of important domestic flies (from Wilson et al. 1977) Some flies disperse many miles from their original breeding site.
More often, the breeding area is nearby, such as a pile of manure- Sanitation is the single most important step in controlling
soaked straw, a rotting potato beneath a cabinet, or a poorly flies. In general, the poorer the sanitation, the greater the fly maintained dumpster behind a restaurant.
problem. However, even small amounts of garbage or waste cansupport hundreds of developing flies. Fermenting goo under food preparation equipment, or a neglected floor mop, can sup- An essential first step in managing fly problems is cor- port a serious infestation of fruit flies. The same is true for a rectly identifying the species involved. This may require the seldomly cleaned floor drain which may be the source of moth assistance of an entomologist. Some of the more common flies or phorid flies. Efforts must be made to find and eliminate domestic flies are shown in the taxonomic key (Fig. 4-2). Proper the breeding source; otherwise, the problem is likely to con- identification is important because this will help to identify tinue regardless of what other control methods are attempted.
possible breeding sites for corrective action. It may also identifyconditions contributing to the infestation, such as poor sanita-tion or inadequate screening of doors or windows.
Fig. 4-2—Taxonomic key for commonly encountered flies (Source: Hedges, Stoy A., PCT Field Guide for the Management of Structure-
Infesting Flies, Franzak & Foster Co., 1994).
Clean garbage cans and dumpsters regularly and keep them covered to prevent attracting flies. Trash should be collected atleast twice a week from residences, and daily from business es-tablishments. Promptly removing waste ensures that if flies dobegin breeding in garbage, they will be removed before a newgeneration reaches the adult stage. Garbage should be buried ina sanitary landfill. Incinerators may be practical for large citieswhere landfills are too remote. Sanitary disposal of sewage andindustrial waste is essential in any municipal fly control program.
Open sewage pits and wastes from canneries, feed mills, poultryand meat packing houses are sources of heavy fly breeding andcan cause more problems in nearby residential areas. Adequatedisposal methods should be available at the plant, or holdingfacilities should be available from which wastes can periodicallybe transported to a sanitary landfill. Public health agencies mustsecure the support of other agencies that will be involved withwaste disposal.
Another very important method of preventing fly prob- lems in buildings is exclusion. Exterior doors and windows
should be properly screened and kept closed whenever prac-
tical. Plastic strip curtains and air doors can be used to deny
fly access in some situations.
Once flies are inside a building, light traps can be used to
capture the winged adults. These traps usually employ ultra-violet (UV) light as an attractant, and kill either by electrocu-tion or entrapment on replaceable, glue-covered cardboardinserts. In order for these traps to be effective, they must beproperly positioned along routes of fly entry and movement.
They must also be installed at the proper height (ideally within5 feet of the floor) and away from windows and other compet-ing light sources. The "glow" of a light trap should not bevisible from outside; otherwise, the trap will attract insectsinto the building when doorways are open. Bulbs should bereplaced each year, and catch pans or glueboards servicedroutinely to prevent dead insects from becoming a food sourcefor other insects (e.g., dermestids).
Bottle or jar traps are also useful for capturing adult
flies. Bottle traps are especially useful for trapping fruit fliesand phorid (humpback) flies, once the breeding source is elimi-nated. (Potential breeding sites for these tiny flies includerotting fruits or vegetables; spillage in trash cans or recyclingbins; unsanitized floor drains; and food-soiled mops or clean-ing rags). A simple jar trap for fruit or phorid flies can be madeby placing a paper funnel into a jar which is then baited with afew ounces of cider vinegar as an attractant.
In most cases, insecticides should be considered a sec- ondary form of fly control after sanitation, exclusion, and trap-ping. Regardless of how effective a treatment may appear,unless you locate and eliminate the breeding source and/orpoint of entry into a structure, the problem will continue.
Moreover, because flies reproduce rapidly, they quickly de-velop resistance to most insecticides.
Various types of insecticide treatments are used in fly control.
• Non-Residual (Contact) Sprays — Temporary control of
adult flies can be achieved by applying synergized pyrethrins
or short-residual synthetic pyrethroids such as allethrin,
sumethrin, or resmethrin. While these insecticides quickly
knock down adult flies, they provide no lasting effect and do
not control developing larvae. Application can be made with
aerosol-type dispensers, ultra low volume (ULV), or fog-gen-
erating equipment. For optimum results indoors, apply the
precise amount of material per cubic area specified on the
label. When performing space treatments, the applicator should
wear goggles and a respirator. He should also ensure that no
people are present, and that any food, utensils, or food prepa-
ration surfaces are covered or washed before reusing.
• Residual Sprays—Residual insecticides are sometimes use-
ful in fly control, but only as a supplement to other methods
already mentioned. Treatments should be applied as coarse
low pressure sprays, confined to surfaces where flies rest and
are likely to absorb a lethal dose (e.g., areas around dumpsters
or sun-exposed exterior walls adjacent to a doorway). Several
different insecticides are registered, including chlorpyrifos,
diazinon, and propoxur. Synthetic pyrethroids (e.g.,
cypermethrin, cyfluthrin) are also very effective, especially
wettable powder or microencapsulated formulations.
• Fly Baits—Baits are a mixture of toxicant and attractant and
are used primarily to control house flies. Most baits contain
sugar and the house fly sex pheromone, muscalure. These keep
the fly in contact with the toxicant for a longer time. Fly baits are
typically formulated as granules which are placed in shallow
trays or scattered around dumpsters and other fly breeding
Fig. 5-1—Wasps, hornets, and yellowjackets
areas. Their effect is short-lived unless the bait is reapplied.
Hornets—Hornets are far more difficult and dangerous
Wasps, Hornets, and Yellowjackets
to control than paper wasps. The nests resemble a large, grey,bloated football, which typically is attached to a tree, bush, or Wasp, hornet, and yellowjacket stings are a serious health side of a building. Hornet nests may contain thousands of threat to humans and animals. Hundreds (perhaps thousands) wasps which are extremely aggressive when disturbed. The of people in the United States die each year from allergic reac- nests are often located out of reach and removal is best ac- tions to the venom of these insects. Wasps, hornets, and complished by a professional pest control firm.
yellowjackets are more dangerous and unpredictable than Treat hornet and yellowjacket nests at night when most
honey bees. Workers foraging away from the nest are seldom wasps are within the nest and the colony is less active. A full
aggressive, but nests should be eliminated with great care wasp suit, sealed at the wrists, ankles, and collar, should be and in a specific manner. "Folk" remedies, such as dousing worn. Apply an aerosol-type wasp and hornet spray, or dust nests with gasoline or a garden hose, seldom work and can formulation, carbaryl (Sevin) or bendiocarb (Ficam), directly result in multiple stings.
into the nest opening. Hornet nests have a single opening, Paper Wasps—Paper wasps (as well as hornets and
usually toward the bottom, where the wasps enter and exit. It yellowjackets) construct nests of a paper-like material con- is critical that the paper envelope of the nest not be broken taining finely chewed wood fragments and salivary secre- during treatment or the irritated wasps will scatter in all tions of the wasps. Paper wasps typically build their umbrella- directions, causing even greater problems. Following treat- shaped nests under eaves and ledges (Fig. 5-1). These brown- ment, wait at least a day before removing the nest to ensure ish wasps are not as aggressive as yellowjackets or hornets, that all of the wasps are killed. If hornets continue to be ob- and can be eliminated rather easily with a wasp and hornet served, the application may need to be repeated.
spray sold at most grocery and hardware stores. One advan- If the nest is located away from frequently used areas, tage of these formulations is that they can be sprayed as far another option is to wait and do nothing. In Kentucky, wasp, hornet, and yellowjacket colonies die naturally after the weather Although it is best to treat all wasps at night, paper wasps turns cold, and the paper carton disintegrates over the winter can be eliminated during the daytime provided you do not stand directly below the nest during treatment. Most wasp Yellowjackets -- Yellowjackets are often considered the most
sprays cause insects to drop instantly. Standing directly un- dangerous stinging insects in the United States. They tend to be der a nest increases the risk of being stung. After treatment, unpredictable and usually will sting if the nest is disturbed.
wait a day to ensure that the colony is destroyed, then scrape Yellowjackets form annual colonies in Kentucky (Fig. 5- or knock down the nest. This will prevent secondary prob- 2). Mated queens overwinter under bark and in other shel- lems with carpet beetles and other insects.
Fig. 5-2—Life cycle of the yellowjacket (modified from Olkowski et al. 1991)
tered locations. In the spring the queens emerge and con- puffs of insecticide dust into the nest opening. A dry, empty struct a small paper nest in which they lay their eggs. Larvae liquid detergent bottle filled no more than halfway with dust and are fed by the queen, and in about a month, emerge as sterile shaken before dispensing also works well. A few pebbles or adult females called workers. The newly emerged workers as- marbles added to the bottom of the bottle prevent caking.
sume all nest activities except egg laying. Thereafter, the colony Treatment should be performed late at night after all
grows rapidly, containing up to 4000 workers by the end of yellowjackets are in the nest and less active. Pinpoint the
the summer. New males and queens are produced in late sum- nest opening during the daytime so you will remember where mer to early fall. After mating, the colony dies off and the to direct your treatment after dark. Approach the nest slowly newly fertilized queens seek out sheltered sites for overwin- and do not shine the beam of your flashlight directly into the tering. Abandoned nests are not reused and soon disinte- nest entrance as this may startle the wasps; instead, cast the beam to the side to illuminate the nest indirectly. If possible, Yellowjacket nests are often located underground in old ro- place the light on the ground rather than in your hand as dent burrows or beneath rocks or landscape timbers.
wasps tend to fly toward light. As with hornets, yellowjackets Yellowjackets also build nests in walls, attics, crawlspaces, and are extremely aggressive when the nest is disturbed. It may be behind the siding of buildings. If the nest can be located, it can prudent to refer homeowners to a pest control operator, par- usually be eliminated by carefully applying a wasp spray insecti- ticularly when access to the nest is difficult.
cide into the nest opening. Dust formulations (e.g., carbaryl, Late-Summer Foraging Activity—During late summer
bendiocarb, Drione®) are also very effective provided a and fall, yellowjacket colonies are nearing maturity and huge handduster or similar type applicator is used to dispense several numbers of workers are out foraging for food for the develop- ing queens. Late in the year, feeding preferences shift in are free-roaming and make no webs. Most spiders are harm- favor of available sources of sugar, including fruits, ice less, and in fact are beneficial, because they prey upon flies, cream, soft drinks, beer, or other sweets. The persistent crickets, and other insects. They generally will not attempt to foraging of yellowjackets at picnics and other outdoor ac- bite humans unless held or accidentally trapped. Moreover, tivities produces many calls from homeowners and busi- the majority of spiders have fangs too small or weak to punc- nesses wanting to know what can be done to alleviate the ture human skin. Of the hundreds of species found in Ken- problem. Options include: tucky, only the black widow and brown recluse are danger- • Sanitation—The best way to reduce the threat of foraging
ous. Fortunately, both are relatively uncommon, and have yellowjackets is to minimize attractive food sources. People markings that can be used to distinguish them from other eating outdoors should keep food and beverages covered.
Spills and leftovers should be cleaned up promptly. Trashcans should be equipped with tight-fitting (preferably self- Black Widow Spider
closing) lids. Similar sanitation recommendations should be Of the spiders capable of inflicting a poisonous bite, black made to commercial establishments, including ice cream par- widows are the most notorious. The female is about 1/2-inch lors, outdoor cafes, and supermarkets. Whenever possible, long, shiny black, and usually has a red hourglass mark on trash cans and dumpsters should be located away from serv- the underside of the abdomen (Fig. 6-1). In some varieties the ing tables, loading dock doors, and other entrances. Trash hourglass mark may be reduced to two separate spots.
cans should be equipped with a plastic liner and emptied and Spiderlings and male spiders are smaller than females and cleaned frequently.
have several red dots on the abdomen's upper side.
Maintaining high levels of sanitation earlier in the sum- Widow spiders belong to the cobweb spider family and mer will make areas less attractive to yellowjackets later in spin loosely organized trap webs. The webs are usually found the year. This strategy is especially useful for parks and rec- outdoors under objects such as rocks and ground trash or reation areas.
• Avoidance—Combined with sanitation, this is the best ad-
vice in most situations. Yellowjackets foraging away from their
nests are seldom aggressive and usually will not sting unless
provoked. People should resist the temptation to "swat" at
the wasps -- and be careful when drinking from beverage cans
which may contain foraging individuals.
Avoidance may also be the best advice if a yellowjacket (or hornet) nest is located in a tree or other out of the way
location. As noted earlier, yellowjacket colonies die off on
their own in late autumn.
• Repellants—A dilute solution of ammonia and water (ap-
proximately 6 ozs of ammonia per gallon of water) sprayed in
and around trash cans and sponged onto outdoor tables and
food preparation surfaces may help to repel yellowjackets
Fig. 6-1—Black widow spider (female)
from these areas. Use household ammonia, not bleach.
• Traps—Although only of marginal benefit, traps are avail-
under an overhanging embankment. Black widow spiders are able which catch impressive numbers of yellowjackets when not as common in homes as the brown recluse. When found properly baited and positioned. Business establishments such in homes, they are usually under appliances or heavy furni- as outdoor cafes may find these traps worthwhile when used ture and not out in the open like other cobweb spiders. Black with other approaches. Braunswagger liverwurst spread com- widow spiders are timid, however, and will only bite in re- bined with jelly has been an effective attractant.
sponse to being injured. People are usually bitten when theyreach under furniture or lift objects under which a spider is Wasp, hornet and yellowjacket stings can be life-threat- Black widow venom is a nerve toxin and its effects are ening to persons who are allergic to the venom. People who rapid. The victim suffers painful rigidity of the abdomen and develop hives, difficulty breathing or swallowing, wheezing, usually a tightness of the chest. Blood pressure and body or similar symptoms of allergic reaction should seek medical at- temperature may rise and sweating, localized swelling, and a tention immediately. Itching, pain, and localized swelling can be feeling of nausea may occur. In about 5% of the bite cases the somewhat reduced with antihistamines and a cold compress.
victim may go into convulsions in 14 to 32 hours and die if notgiven medical attention. First aid for black widow spider bites involves cleansing the wound and applying ice packs to slowabsorption of venom. Victims should seek medical attention Many different kinds of spiders live in and around build- promptly. Most black widow spider envenomizations respond ings. Some, such as garden and cellar spiders, construct webs to intravenous administration of calcium gluconate or calcium to help entrap their prey. Others, including the wolf spiders, salts. An antivenin is also available for severe cases.
1. Routine, thorough house cleaning is the best way to elimi-
Brown Recluse Spider
nate spiders and discourage their return. A vacuum cleaner The brown recluse (Fig. 6-2) is about the size of a black or broom effectively removes spiders, webs, and egg sacs. widow but is not so readily distinguished from many other 2. Spiders prefer quiet, undisturbed areas such as closets,
spiders. It ranges from a dark cream color to dark brown. The garages, basements, and attics. Reducing clutter in these abdomen is darker than the rest of the body. It has a violin- areas makes them less attractive to spiders. shaped, dark mark on top of the leg-bearing section of the 3. Large numbers of spiders often congregate outdoors around
body and therefore is sometimes called the "fiddler or violin" the perimeter of structures. Migration indoors can be re- spider. Brown recluse spiders also have 3 pairs of eyes rather duced by moving firewood, building materials, and debris than 4 pairs for most other spiders.
away from the foundation. Shrubs, vines and tree limbs should The brown recluse roams at night seeking its prey. Dur- be clipped back from the side of the building. ing the day, it hides in dark niches and corners, where it mayspin a poorly organized web. It is shy and will try to run from 4. Install tight-fitting window screens and door sweeps to
exclude spiders and other insects. Inspect and clean behind
outdoor window shutters.
5. Consider installing yellow or sodium vapor light bulbs at
outside entrances. These lights are less attractive than mer-
cury vapor, fluorescent, or incandescent bulbs to night-fly-
ing insects which, in turn, attract spiders.
6. To further reduce spider entry from outdoors, insecti-
cides can be applied as a "barrier treatment" around the
base of the foundation. Pay particular attention to door
thresholds, garage and crawl space entrances, including
foundation vents. Carbaryl, bendiocarb, chlorpyrifos, or
any of the synthetic pyrethroids (e.g., cypermethrin,
cyfluthrin, lambda-cyhalothrin) are effective, but may need
to be reapplied periodically throughout the summer. Wet-
table powder or microencapsulated "slow-release" for-
mulations are most effective.
Fig. 6-2—Brown recluse spider
The brown recluse may be found living indoors or out- a threatening situation but will bite if cornered. People are doors while black widows are more often encountered out- sometimes bitten while they are asleep because they roll onto doors. Thorough inspection of cracks, corners, and other dark, a brown recluse spider while it is hunting in the bed. More undisturbed areas with a bright flashlight will help determine often the victim is bitten while putting on a shoe or piece of the location and extent of infestation. Both species construct clothing which a spider has selected for its daytime hiding irregular, nondescript webs. Indoors, pay particular attention to basements, attics, crawl spaces, closets, under/behind beds The bite of the brown recluse is usually painless until 3 to and furniture, inside shoes, boxes of stored items, and be- 8 hours later when it may become red, swollen, and tender.
tween hanging clothing. Brown recluse spiders also may be Later, the area around the bite site may develop into an ulcer- found living in drop ceilings, behind baseboards, and inside ous sore from 1/2 to 10 inches in diameter. Healing often re- ductwork or registers. Another way to detect infestations in quires a month or longer, and the victim may be left with a these areas is to install glueboards or sticky traps. These deep scar. Prompt medical attention can reduce the extent of devices can be purchased at grocery or farm supply stores.
ulceration and alleviate other complications that may develop.
Placed flush along walls and in corners, glueboards and sticky In rare cares, the bite can produce a severe systemic reaction traps are useful monitoring tools and will also capture large resulting in death.
numbers of spiders.
Persons bitten by a spider which they think is a brown Brown recluse and black widow spiders also live out- recluse should try to collect the specimen and bring it to a doors in barns, utility sheds, woodpiles, and underneath lum- qualified individual for identification. Positive identification ber, rocks, and accumulated debris. To avoid being bitten, by an expert will help the physician decide on the appropriate wear work gloves when inspecting inside boxes or when mov- course of treatment.
ing stored items.
Each of the management tips (1-6) noted above for spi- ders in general is also useful against the black widow and Eliminating an infestation of brown recluse or black widow brown recluse. Removal of unnecessary clutter is especially spiders involves two basic principles: (1) altering the environ- helpful in making areas unattractive to these pests. Indoor ment in and around a building to make it less attractive to infestations of brown recluse and black widow also warrant spiders; and (2) finding and destroying as many spiders as treatment with insecticides. Insecticides should be applied possible. The following measures can be used to control all into areas where spiders are living, making an attempt to con- tact as many spiders and webs as possible with the treatment.
Spot treatments with synthetic pyrethroids such as cyfluthrin,cypermethrin, or lambda-cyhalothrin are especially effective.
Most household insecticides with spiders listed on the labelwill also kill spiders provided the spider is treated directly. Ininaccessible or cluttered areas such as attics and storage sheds,total-release foggers or aerosols containing synergized pyrethrinor synergized pyrethroids (e.g. resmethrin,sumithrin,cyfluthrin)will have a better chance of contacting spiders that are hidden.
Severe infestations of brown recluse or black widow spi- ders require specialized skills and equipment to eradicate. Inthese situations, it would be prudent to call a professionalpest control operator.
Rats and mice are remarkably well-adapted for living in close association with humans. The greatest economic loss isnot from how much these rodents eat, but what must be thrownout because of damage or contamination. Food, clothing, fur-niture, books, and many other items are contaminated by theirdroppings and urine or damaged by their gnawing. Rodentsdamage doors, walls, insulation, and other structural compo-nents by their gnawing and burrowing. They also gnawthrough utility pipes and electrical wiring, causing fires, in-door flooding, power outages, and equipment failure.
Rats and mice can also transmit diseases, most notably salmonellosis (bacterial food poisoning), when food is con-taminated by infected rodent feces. Other rodent-borne dis-eases include plague, murine typhus, rat-bite fever, rickettsialpox, and hantavirus.
Description, Biology, and Habits
Fig. 7-1—Common domestic rodents (from Bennett et al. 1988). Three common species of rodents live in close associa- tion with humans: the Norway rat, roof rat, and house mouse.
Roof Rat—Roof rats are much less common in Kentucky,
Norway Rat—The Norway rat (Fig. 7-1), also called the
but are occasionally encountered. These rats are smaller and brown or sewer rat, is the largest domestic rodent. An adult sleeker than the Norway rat, weighing about 8 to 12 ounces weighs about 12 to 16 ounces, and the body is stocky and when fully grown. The tail is longer than the combined length covered with coarse, reddish brown fur. The head is small, of the head and body, the muzzle is pointed, and the ears are with close-set ears and a blunt muzzle. The tail is shorter than the combined length of the head and body. Adult droppings Roof rats are excellent climbers and are usually found are about 3/4-in long, capsule-shaped, with blunt ends.
above ground level. Nests may be located indoors, in attics, Norway rats live about one year and reach sexual matu- roof areas, or ceiling voids. Roof rats often enter buildings by rity in 2 to 3 months. Females have 4 to 6 litters each year with using tree limbs, utility lines, or fences. They also nest out- 6 to 12 young per litter.
doors, in trees, vines, or on the roof or sides of buildings.
Outdoors, Norway rats commonly nest in burrows along- Occasionally, they will nest in underground burrows like the side buildings, fences, and under bushes or debris. They use the same routes daily and their feet make a beaten path along Roof rats consume many types of foods, but prefer veg- the ground. Indoors, Norway rats prefer to nest in the lower etables, fruits, seeds, and cereal grains. Droppings are about portions of buildings in wall voids, underneath floors, in 1/2-inch long and spindle shaped (pointed) on one end.
crawlspaces, and beneath or inside equipment or stored items.
House Mouse—The house mouse is the smallest domes-
Norway rats eat essentially the same foods as humans, tic rodent. Adults are 2 1/2- to 3 1/2-inches long, with a 3- to 4- including meats, vegetables, and cereal grains, as well as gar- inch semihairless tail. House mice are gray to brown, and have bage. They require water each day when feeding on dry food.
large ears. Mouse droppings are 1/8- to 1/4-inch long with at Rats tend to be more cautious than mice in their foraging and least one of the ends pointed.
feeding habits. Their average foraging range from the nest is House mice only live about a year, but are prolific breed- about 50-150 feet, but will travel further if food or water is ers. Females produce 6 to 10 litters continuously throughout scarce. Like all commensal rodents, Norway rats are nocturnal the year with 4 to 7 young per litter. House mice may live (active primarily at night), and they prefer to travel adjacent to indoors or outdoors. Outdoors, they often live among weeds walls and edges.
and shrubbery or near building foundations, inside garages, 4) Tracks—Rodent footprints or tail marks can sometimes be
crawl spaces, or outbuildings. When food becomes scarce in found on dusty surfaces or in mud. To better see tracks in the fall, mice often move indoors. Inside buildings, mice com- dust, hold a flashlight so that the beam is directed across the monly nest within walls, ceiling, and cabinet voids, furniture, tracks at an angle. A tracking patch made of talc or flour can and large appliances.
further help to determine if rodents are present.
Mice feed on a wide variety of foods but prefer seeds and 5) Gnawing Marks—Mice and rats gnaw on all types of ob-
cereal grains. They are also fond of foods high in fat and jects. Mice often gnaw small, clean-cut holes about one inch protein such as nuts, bacon, butter, and sweets (a useful point in diameter in boxes, bags, door sweeps, etc. Gnaw holes from to remember when selecting baits for snap traps). Mice are rats are larger (about 2 inches in diameter), and often contain "nibblers" and may make 20 to 30 visits to different food sites rough, torn edges. Rats often gnaw on the bottom of wood each night. Compared to rats, mice forage only short distances doors, joists, and other structural members.
from their nest, usually not more than 10-25 feet. When foodand shelter are adequate, their foraging range may be only a few feet. For this reason, traps and other control devices must Rodents must have food and shelter to survive. What- be placed in areas where mouse activity is most apparent.
ever can be done to limit availability of these essential re- Similar to rats, mice prefer to travel adjacent to walls and other sources will help to reduce rodent problems. This is espe- edges (another important point to remember when position- cially true for rats, which require considerably more food, water, ing control devices). Mice are very inquisitive and will inves- and shelter than do mice. Garbage should be kept in rodent- tigate each new object placed in their foraging territory. There- proof containers and picked up regularly. The same is true for fore, if control devices are not initially successful, try moving pet food and bird seed. Weeds and unnecessary vegetation them to a different location.
should be removed, especially when they are adjacent to build-ing foundations. (Weed seeds are a favored food of mice and also serve as rodent harborage). Rubbish, lumber, rock piles, To control rats and mice, you must "think like a rodent." and old equipment should be eliminated, as should standing Keep in mind the behavioral traits noted above for each spe- water. Where practical, boxes, crates, and other items should cies. Begin with a thorough inspection of the premises, rely- be stored at least 18 inches off the ground and 12 inches away ing on the following signs as indicators of rodent activity: from walls. Storing items in this manner makes them less at- 1) Droppings are the most common indicators of rodent pres-
tractive to rodents. It also facilitates inspection, cleaning, and ence and provide valuable clues where to place control de- installation of rodent control devices.
vices. They are likely to be found where rodents travel, neartheir shelters, or other places rodents frequent. The shape and number of droppings can tell the species of rodent in- Along with proper sanitation, the best way to avoid ro- volved, the approximate size of the infestation, and whether dent problems in buildings is to prevent their entry. Mice are the infestation is old or new. Fresh droppings are usually soft, able to squeeze through extremely small openings no wider shiny and dark but can become hard in a matter of hours. Old than the diameter of a pencil (1/4-inch). Rats can enter through droppings are dull and often covered with dust. Active infes- cracks the size of a quarter (1/2-inch). Cracks and openings tations can best be determined by removing old droppings under doors, around windows, in building foundations, vents, and noting the presence of new droppings.
and where plumbing, electrical, and air conditioning lines en- 2) Runways/Rub Marks—Rodents are creatures of habit. They
ter the structure should all be sealed (Fig. 7-2). Permanent consistently use the same routes between food, water, and sealants such as cement, sheet metal, and hardware cloth are harborage. Outdoors, runways can be found next to walls, along fences, and under vegetation. Active runways aresmooth, well packed, and free of vegetation. Indoors, run- Traps and Glue Boards
ways may be found along walls, edges, and between stored Trapping can be a very effective form of rodent control, items. As a rat moves along walls and through tight spaces, especially against mice. If signs indicate that you do not have its body hairs often leave a dark, greasy deposit on surfaces.
a large rodent population, traps are generally preferred over These "rubmarks" may be seen at ground level (along floor- pesticides because they are less hazardous to use around wall junctions) or overhead beneath beams and rafters.
children and pets. In addition, because rodents are captured 3) Burrows—The Norway rat prefers to nest in burrows,
by the trap, they are not as likely to die in walls or other whereas the roof rat and house mouse only burrow occasion- inaccessible areas and create odors. Snap traps (Fig. 7-3) are ally. Rat burrows are usually found under concrete slabs, along- widely available and easy to use. Trapping efficiency can be side building foundations, or beneath shrubbery and debris.
enhanced by baiting the trigger with such foods as peanut Active burrows usually are smooth and compacted at the en- butter, bacon, raisins, or fruit. Snap traps with an expanded trance, and free of dust and cobwebs. To determine if a bur- trigger catch significantly more mice than conventional de- row is active, stuff wads of paper into the opening or cave in signs. Snap traps should be oriented perpendicular to the the burrow with soil and recheck it the following day. Rat wall, with the trigger end against the vertical surface.
burrows usually consist of a main entrance and two or more Another very effective trap against mice is the automatic, "bolt" holes.
multiple-catch trap (Fig. 7-4). Mice enter these traps out of STOPPAGE OF OPENINGS AROUND PIPES
DRAIN COVER SCREENING
RODENT PROOFING OF A VENT
RODENT PROOFING OF A DOOR
Fig. 7-2—Rodent proofing common entry points. dent control devices should also be installed in areas wherethere is potential for rat or mouse entry (e.g., on both sides ofexterior doors, and near utility openings in walls).
Rodents have limited foraging ranges, therefore, it's im- portant to use several trap placements. For mice, traps andglue boards should be spaced no more than 10 feet apart inareas where mouse activity is apparent -- closer if the infesta-tion is severe. Rat traps can be spaced 15 to 20 feet apart.
Traps and glue boards should be checked daily, and dead rodents disposed of in plastic bags. Gloves should be wornwhen handling rodent carcasses to prevent any chance ofdisease spread. Records should be kept indicating where eachcontrol device was installed and which placements caughtrodents. Decomposing rodents attract flies, dermestids, andother insects which can lead to additional problems if notremoved. Keeping trap catch records also helps to identifypersistent areas of rodent activity. Adjustments to the rodentcontrol activities in these areas (e.g., adding more traps, ex-clusion, weed control) can then be made accordingly.
Fig. 7-3—Position snap traps flush against wall with trigger againstvertical surface (note expanded trigger design) Specific pesticides, known as rodenticides, are available curiosity for new objects placed in their territory. One type of for rodent control. The three main types are poison baits, multiple-catch trap requires winding and flips mice into a hold- tracking powders and fumigants.
ing chamber. Another model operates using the principle of a trap door. Both devices can capture and hold several micebefore needing to be emptied. Multiple-catch traps can be Most rodenticides are formulated as food-based baits oriented with the entrance hole either perpendicular or paral- containing seeds or grain to attract the rodents. Many baits lel to the wall.
are anticoagulants containing brodifacoum, bromadiolone, Glue boards are also very effective against rodents, es- chlorophacinone, diphacinone, or warfarin as active ingredi- pecially mice. Mice become entangled in the glue when they ents. These toxicants kill by interfering with normal clotting ofthe rodents' blood, causing the rodent to die from internalbleeding. The newer anticoagulants (e.g., brodifacoum,bromadiolone) are normally lethal to rodents after a singlefeeding. Nonetheless, 3 to 5 additional days are typically re-quired for the rodent to die. The older anticoagulants (war-farin, chlorophacinone, diphacinone) required severalfeedings by the rodent, and two or more weeks for death tooccur.
Non-anticoagulant rodenticide baits are also available.
Most of them kill rodents after a single feeding. Bromethalinkills rodents in 2-3 days by causing paralysis of the nervoussystem. Cholecalciferol causes an excess of calcium in theblood, leading to heart failure in 3-4 days. Zinc phosphidekills rodents in 1-24 hours by forming phosphine gas in the Fig. 7-4—One type of automatic multiple-catch trap. circulatory system.
run over the boards. Captured mice soon die of suffocation.
Commercial baits, in pelleted or meal form, are avail- Along with traps, glue boards are a preferred method of con- able in sealed plastic, cellophane or paper packets (known as trol in homes and other sensitive locations where pesticides "place" packs), as loose bait, or molded into paraffin (wax) are a concern. Glue traps can be purchased ready made, or can blocks. The wax block formulation is very useful for both be custom made using bulk glue and plywood cut to varying outdoor and indoor baiting locations because it resists damp- sizes to fit the particular job requirements. Should the glue ness and moisture. Regardless of which bait formulation is from a glue board contact the fur of a pet or the skin of a child, used, extreme care must be taken to position baits in areas it can be removed with mineral or vegetable oil.
inaccessible to children, pets, and wildlife or in tamper-re- Regardless of which type of trap or glue board is used, sistant bait stations. Dogs, in particular, will seek out and find placements should be installed up against walls, behind baits placed in areas that are accessible.
objects and appliances, and in secluded areas where drop- Other than when placing baits directly into a rodent bur- pings, damage, and other signs of rodents are evident. Ro- row, it makes good sense to confine baits in an enclosed bait box (Fig. 7-5). Bait boxes help to (1) reduce accidental contact with people and non-target animals, (2) keep bait fresh by Certain rodenticides are also formulated as poisonous protecting it from dirt, moisture, and dust, (3) provide a pro- gases (fumigants). The most common use of these products tected and attractive place for rodents to feed, and (4) allow is for burrow gassing. Gassing rodent burrows with a fumi- label, company contact number, and other pertinent informa- gant is a fast and effective way to control burrowing rodents tion to be provided at the baiting site. If rodent bait cannot be (e.g., Norway rats) in outside locations. The most common installed in locations inaccessible to children and non-target fumigant used for burrow gassing is aluminum phosphide,
animals, it must be placed in tamper-resistant bait boxes.
formulated as tablets or pellets. The product is placed in the These boxes are constructed of metal or non-crushable plas- burrow with a gloved hand, and the gas releases slowly as it tic, are equipped with a locking mechanism, and have a spe- reacts with ground moisture in the burrow. Fumigants can be cific internal design for confining bait within the station. In extremely dangerous if used incorrectly. Applicators should order to be considered truly tamper-resistant, the station must always remember to read the pesticide label before use.
also be secured to the mounting substrate (ground, floor, wall,fence, etc.). This can be done with a stake, nail gun, length of chain, "liquid nails," or by securing the station to a weightedpaving block.
Pigeons, starlings, and sparrows (Fig. 8-1) cause millions As with traps, proper bait placement is critical. Place bait of dollars in damage by defacing buildings, sidewalks, cars, in all areas suspected of harboring rodents, along routes of etc., with their droppings. Downspouts and air vents maybecome stopped up by nesting materials. Bird feathers, filth,and carcasses can lead to secondary pest problems by at-tracting carpet beetles, mealworms, and other scavengers.
Fig. 7-5—Bait boxes enhance bait effectiveness and help preventaccidental poisoning. Place bait stations flush against walls andalong rodent runways. travel, and where they are likely to enter the building. Severalplacements will produce better results than just a few. Baitsthat are not being fed upon may need to be repositioned.
Rodent bait should be replaced at least monthly because ratsand mice are not attracted to old, moldy bait.
Fig. 8-1—Pictorial key to common pest birds. Birds nesting around buildings also constitute a health Some rodenticides are formulated as "toxic dusts," hazard to people and animals. Ectoparasites such as mites, known as tracking powders. Tracking powders may contain
lice, and bedbugs can invade living areas and bite humans anticoagulants (e.g., chlorophacinone, diphacinone) or non- after the nestlings leave or a bird dies. Birds can also transmit anticoagulants (e.g., zinc phosphide) as toxicants. Small serious diseases, including cryptococcosis and histoplasmo- amounts of tracking powder are placed in known rodent sis — systemic fungal infections acquired by inhaling air- runways, burrows, wall voids, and other concealed borne spores which grow in bird droppings.
locations, usually via a hand duster. Rodents pick up thetoxicant on their fur and feet and ingest it while grooming.
Bird Management Options
Tracking powders are especially effective against mice, Non-Lethal Controls—The most effective way to avoid
which groom themselves and their nestmates continuously.
problems with pest birds around buildings is to deny them Tracking powders should only be placed in inaccessible nesting and roosting sites. The best time to do this is before areas or in the bottom of tamper-resistant bait stations. As nests are well established. Vents and other small openings with any pesticide, care must be taken not to contaminate should be sealed with 1/4-inch hardware cloth or similar exclu- food preparation surfaces or other surfaces that may be sion materials. Attic vents may need to be screened or netted contacted by people or pets.
on the exterior, to prevent sparrows from nesting betweenthe louvers. Nesting or roosting on ledges, eaves, windowsills, and other surfaces can be deterred by installing tightly strung, parallel strands of wire just above the surface of the roosting, loafing, or feeding sites. Success of live trapping ledge. Roosting of pest birds can also be discouraged by can be enhanced by pre-baiting traps with corn or milo for changing the angle of the ledge to 45 degrees or more with several days before actual trapping begins.
sheet metal or wood boards. "Porcupine" wires (e.g., Nixalite®, Lethal Controls—Toxic perches are registered for the
Cat Claw®) or coils (Bird Barrier ™ ), repellent gels, or bird control of pigeons and starlings roosting around buildings.
netting also are effective, provided they are correctly installed Perches are hollow tubes that hold about an ounce of toxicant and a wick to transfer the toxicant to the birds' feet. Birdslanding on the treated perch absorb the pesticide rapidly anddie within 24 to 72 hours. The active ingredient used in mosttoxic perches (e.g., Rid-A-Bird ®) is fenthion. Because of theirpotential hazard to non-target birds, animals and people, toxicperches are classified as Restricted Use Pesticides, and shouldbe used only by trained personnel. In order to be effective,perches must be installed in areas where birds routinely roost.
Toxic perches are prohibited inside food storage, handling,and processing facilities.
Toxic Baits can also be used to reduce pest bird popula-
tions. Commonly used products include Avitrol (for pigeons,
starlings and sparrows) and Starlicide (for starlings). Avitrol
is available in corn or mixed grain formulations of which a
small number of grains or kernels are treated with a toxicant.
Birds that eat the treated particles of bait behave erratically
and emit warning cries. These birds, in turn, frighten other
birds in the flock to leave the area. Birds that eat the treated
Fig. 8-2—Commonly usedtechniques for bird exclusion bait particles usually die. Different levels of mortality and flock- (a) Changing angle of ledge to 45 alarming response can be achieved by varying the ratio of degrees by installing board or sheet treated to untreated bait. Starlicide produces a slow, non-vio- lent death in starlings, usually within 24 to 36 hours after (b) Porcupine wires prevent roosting on ledge Toxic bird baits are Restricted-Use-Pesticides that require (c) Netting excludes birds from experience to use safely and effectively. Selection of baiting rafters and other nesting sites sites requires knowledge of daily bird activity patterns, espe- (d) Repellent gel applied to ledge cially where the flock is feeding. Pre-baiting with untreated with caulking gun bait is important in order to condition the birds to feed on thebait toxicant. Baiting must be carefully monitored to ensure Before installing the screening, remove nests and drop- that no non-target birds such as doves or songbirds are at- pings to avoid problems with scavenger insects and disease tracted to the bait.
pathogens. Gloves and a respirator (dust masks are insuffi- Shooting of birds should be avoided and in many areas is cient) should be worn to avoid inhaling fungal and bacterial illegal. Large or complicated bird jobs may require the ser- spores. Lightly moistening droppings and nesting materials vices of a professional pest control operator or nuisance wild- with water before removal reduces the tendency for spores to life control expert.
become airborne.
Frightening devices can be used to disperse birds, but are often ineffective and require persistence and proper tech- Itches, Irritations, and Delusions
nique. Fake owls, snakes, balloons, and other visual repel- Once in a while, nearly everyone experiences the irrita- lents often fail because birds soon become acclimated to these tion of an unexpected itch or the sensation of something crawl- objects and ignore them. If these devices are tried, reposition ing over the skin. Other times, the irritation may feel more like them periodically or vary the pattern. Noise devices (e.g., dis- an insect bite. These reactions can become so annoying for tress call cassette tapes, noise bombs, whistle bombs), can be some people that they are forced to seek professional help.
effective for dispersing small roosts of birds such as star- Even though actual pests may not have been observed, the lings, but require persistence. Noise frightening efforts should irritation is often attributed to "bugs," and an insecticide is preferably begin before the flock has formed a strong attach- applied in the hope that the problem will be resolved. Unfortu- ment to the site. Noise-producing devices should be acti- nately, pesticides seldom work in these situations, and they vated before dark, as soon as the birds begin to appear at the may even cause irritation and additional health problems.
roost. If frightening efforts are to be successful, they must As a public health professional, you should be aware continue for several consecutive nights.
that there are many potential causes of itching and irritation In the case of pigeons, small populations can often be other than pests. Allergies, cosmetics, medications, and envi- controlled by capturing them in live traps placed near their ronmental contaminants all can produce reactions similar to insect bites. While this makes the experience no less real or bird or rodent dies or the young leave the nest, thousands unpleasant for the affected individual, it underscores the im- of parasitic mites may migrate indoors and bite humans.
portance of keeping an open mind to the possibility of non- Bird and rodent mites are smaller than fleas and lice, but if insect causes of such reactions. Much like a detective, you you look closely they will appear as tiny, dark specks that should attempt to rule out all potential sources of irritation through the process of elimination.
There are two notable exceptions where mites may be the source of irritation but are too small to be seen with the naked Sources of Irritation
eye. The human itch (scabies) mite burrows into the skin, Itches and real or perceived bites of unknown origin can causing intense itching and irritation. Skin between the fin- usually be attributed to one of four general sources: (1) ob- gers, the bend of the elbow or knee, and the shoulder blades scure biting arthropods (e.g., insects or mites), (2) personal are areas most often affected. The intense itching is accompa- use products, (3) environmental factors, or (4) health-related nied by a rash. Scabies is readily diagnosed and treated by conditions. Specific agents most often implicated as irritants most physicians.
are summarized in Table 9-1 and discussed in detail below.
Chiggers also bite people and generally are too small to be seen without magnification. Chiggers live outdoors in tall Obscure Biting Arthropods
weeds and grass. They crawl onto people and move upward In some cases, insects or minute, biting mites prove to be until they encounter a point of constriction between skin and the source of irritation. Although these pests are quite small, clothing, such as around the ankles, behind the knee, or at the most are visible upon close examination (Figure 9-2). The lo- waistline. Chigger bites produce a hardened, red welt which cation and appearance of bites or welts on the body is an- begins to itch intensely within 24-48 hours. Consequently, other key consideration in determining if pests are causing people may not associate the irritation with the fact that they the irritation as well as which species is involved.
were bitten while walking outdoors a day or two before. De-layed irritation following a "bug" bite is also common withsuch pests as mosquitoes and ticks, as well as with the con-tact dermatitis which results from exposure to poison ivy/poison oak.
Mosquitoes, ticks, and a limited number of other arthropods may also bite people, but these pests are usually
large enough to be seen at the time the irritation is felt. The
vast majority of insects and related pests encountered in homes
and buildings cannot bite people; yet, they are often blamed
for itching or irritation caused by other factors.
If a person believes that insects too small to be seen are crawling over his or her skin, strips of clear cellophane tapemay be patted over the affected area as the "crawling" sensa-tion is occurring. Most small biting arthropods move slowlyand will be picked up by the tape if present. Tape samplesshould be attached to a white index card and labeled to indi-cate from where they were collected.
Fig. 9-2--Arthropod pests most often responsible for bites and itches of unknown origin: (a) flea, (b) louse, (c) bird mite, (d) chigger, (e) There are literally hundreds of non-insect agents capable scabies mite. Note scale indicating actual size. of causing itching and irritation. Household products are in- Fleas are the most common source of insect bites within volved far more often than are pests and may cause skin reac- homes. Although fleas are small (1/8") and fast-moving, they tions similar to insect bites. Products most often implicated are large enough to be seen. They usually bite people around include phosphate detergents, soaps, cosmetics, ammonia- the ankles, producing a small, red, hardened, and slightly raised based cleaning agents, hair products, medications, printing welt. Fleas are most often associated with pets, although the inks (especially from multiform carbonless carbon paper), and presence of mice, rats, squirrels, skunks, or raccoons can also certain types of clothing, particularly those which contain fire result in fleas infesting a home.
retardants. If a connection can be made between irritation and Lice may also cause intense itching and irritation. Infes- exposure to one of these potential irritants, avoiding further tations occur on the head and other hairy areas of the body.
exposure may correct the problem. A dermatologist can usu- Lice are tiny, grayish-white insects, but are visible under close ally confirm that a product, rather than a pest, is causing the Mites are very tiny arthropods which occasionally in- fest structures and bite people. In most cases, the infesta- tion can be traced to birds nesting in an attic or on a win- When two or more individuals experience irritation in the dow ledge, etc., or to an infestation of mice or rats. When a absence of pests, the cause is likely to be environmental con- ditions or contaminants dispersed in the air. The irritant(s) ture; these tend to make skin more sensitive. A skin moistur- may be either physical or chemical in nature.
izer is often helpful in these situations.
Physical irritants—The most common physical irritants
Airborne chemical irritants—Indoor air pollution can
are tiny fragments of paper, fabric, or insulation (Figure 9-3).
be a serious problem in modern office buildings and other When these fibers contact the skin, they can produce symp- energy-efficient structures where air is recirculated over and toms ranging from a "crawling sensation" to intense itching over. Indoor air pollution can also be a problem in homes. As accompanied by a rash, welts, or open sores. If fibers or frag- the concentration of chemical contaminants in the air in- ments are involved, the irritation is usually generalized, oc- creases, people may experience dizziness, headaches, and eye, curring over exposed areas of the body such as arms, legs, nose, or throat irritation. Certain air-borne contaminants can neck, and head.
also produce rashes and skin irritation similar to insect bites.
Chemical contaminants most often responsible for thesereactions include ammonia-based cleaning agents, formal-dehyde emitted from wall and floor coverings, tobaccosmoke, and solvents and resins contained in paints, glues,and adhesives.
Reactions to airborne chemicals most often occur in build- ings with inadequate ventilation, especially those that arenew or have been refurbished with new paint or wall or floorcoverings. If indoor air pollutants rather than insects are sus-pected, contact an industrial hygienist. These specialists areequipped to monitor ventilation levels and the presence ofallergy-producing contaminants. Companies specializing inenvironmental health monitoring have listings in the telephone Fig. 9-3—Tiny fragments, such as these paper splinters (a) and directories of most metropolitan areas.
insulation fibers (b), can cause itching and irritation often mistakenfor insect bites. Health-related conditions may be responsible for irrita- Irritation produced by paper fragments is especially common tion mistakenly attributed to insects. Itching and skin irrita- in offices where large quantities of paper are processed daily.
tion are common during pregnancy (especially during the last Continuous-feed paper from computers and multi-page forms trimester) and may also occur in conjunction with diabetes, generate large amounts of fragments, resulting in accumula- liver, kidney, and thyroid disease, and herpes zoster (shingles).
tions on desktops and other surfaces. Newly installed or badly Food allergies are another common cause of itching and irrita- worn synthetic carpet, drapes, or upholstery also shed fibers which can irritate skin.
One's emotional state can likewise induce skin reactions Other potential sources of irritation are insulation fibers that can be mistaken for insect bites. Stress and conflict at released into the air by heating/cooling systems in need of work or home can produce itching and irritation. The itching repair and sound-deadening fibers embedded into drop-ceil- response can be induced in other individuals simply by the ing tiles. These latter sources are especially suspect if there "power of suggestion"; i.e., when one person in a group feels have been problems with the air-handling system or recent an itch or bite and begins to talk about it, others also feel the repair work on the ceiling.
urge to scratch as well (a condition known as Bell's syndrome).
Irritation is aggravated by static electricity which increases Delusions of parasitosis is a more serious emotional
the attraction of the tiny charged fibers to exposed skin. Low disorder characterized by an irrational fear that living or- humidity, electronic equipment, and nylon (e.g., from carpet- ganisms are infesting a person's body. Cases of delusory ing, upholstery, or women's stockings) all increase levels of parasitosis often have similar symptoms and patterns of static electricity and the potential for problems from fragments behavior. Patients typically report "bugs" invading their or fibers. Static electricity may also cause body hair to move, ears, nose, eyes, and other areas of their body. The "crea- giving the impression of insects crawling over the skin.
tures" frequently disappear and reappear and change col- If fibers or fragments are suspected of causing the reac- ors while being observed. Specimens brought in for identi- tions, floors, rugs, work surfaces, and furniture should be fication usually consist of bits of dead skin, hair, lint, thoroughly and routinely vacuumed, and desktops and tables and miscellaneous debris. The skin of the individual is of- wiped down with a damp cloth. Static-reducing measures ten severely irritated from desperate scratching, excessive should also be considered such as raising the humidity level bathing, and application of ointments. While these occur- of the air and installing static-resistant mats and pads under rences may seem bizarre to persons who are not affected, chairs and electronic equipment in offices. Anti-static sprays they are frighteningly real to the patient. Delusions of para- can be used to treat seat cushions and nylon stockings.
sitosis as well as other suspected emotional or medical Dry air alone can cause irritation, producing a condition conditions should be brought to the attention of a derma- known as "winter itch." As skin loses moisture, itching re- tologist or other physician.
sults. A similar reaction can occur from changes in tempera- Finding a Solution
look carefully. Pesticides should not be applied unless there There is no easy way to pinpoint the cause of so-called is actual evidence that pests are the cause of irritation.
"invisible" itches. The most important consideration in deter- Most often, pests will not be involved and relief from irrita- mining if pests are involved is whether or not anyone has tion will lie outside the realm of pest control. Approaching these actually seen or captured any "bugs" as the itching or irrita- problems in a rational and methodical manner will increase the tion is occurring. As noted earlier, most insects and mites that chances of finding other likely sources of irritation. Refer to the bite humans can be seen without magnification if you list of likely irritants in Table 9-1 and follow suggestions thatwere mentioned earlier for alleviating the condition.
Table 9-1. Principal Causes of Itches and Bites of Unknown Origin
Obscure Biting Arthropods*
• mites (e.g., bird, rodent, scabies)
• lice
• fleas
• chiggers
• biting midges/mosquitoes
• ticks
• bedbugs
• detergents (especially phosphate-based)
• soaps
• cosmetics/hair products
• ammonia-based cleaners
• medications
• printing inks (e.g., carbonless)
• clothing (especially fire retardant)
A. Physical irritants
• paper, fabric, or insulation fibers
• low humidity
• seasonal changes in temperature
• static electricity
B. Chemical irritants
• formaldehyde (e.g., from particle board, wall and floor coverings
• ammonia
• solvents/resins associated with paints and adhesives
• tobacco smoke
• volatiles from asphalt and tar installation
• pregnancy
• communicable diseases (e.g., chicken pox, measles)
• stress
• diabetes, liver, or kidney disorders
• food allergies
• insect phobias
*Many of these pests are large enough to be seen without magnification. One should also consider the possibility of delayedirritation such as from bites obtained while outdoors. Where trade names are used, no endorsement is intended, nor criticism implied of similar products not named. Educational programs of Kentucky Cooperative Extension serve all people regardless of race, color, age, sex, religion, disability, or national origin. Issuedin furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, M. Scott Smith,Director of Cooperative Extension Service, University of Kentucky College of Agriculture, Lexington, and Kentucky State University, Frankfort. Copyright 2005 for materials developed by University of Kentucky Cooperative Extension. This publication may be reproduced in portions or its entirety foreducational or nonprofit purposes only. Permitted users shall give credit to the author(s) and include this copyright notice. Publications are also available onthe World Wide Web at www.ca.uky.edu.

Source: http://www.harrisoncountyhealth.com/Bedbugs_&_other_pests_UK_36_pgs.pdf