Chapter 4—Disease Vectors and Pests

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1

Disease Vectors and Pests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1

Rodents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1

Cockroaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4

Fleas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6

Flies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-7

Termites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-8

Fire Ants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-13

Mosquitoes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-15

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-17

Figure 4.1. Field Identification of Domestic Rodents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2

Figure 4.2. Norway Rat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2

Figure 4.3. Roof Rat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2

Figure 4.4. Signs of Rodent Infestation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3

Figure 4.5. Rodent Prevention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4

Figure 4.6. Live Trap for Rats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4

Figure 4.7. Kill Traps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4

Figure 4.8. American, Oriental, German, and Brown-banded Cockroaches . . . . . . . . . . . . . . . . . . . . . . .4-5

Figure 4.9. American Cockroaches, Various Stages and Ages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5

Figure 4.10. Oriental Cockroaches, Various Stages and Ages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5

Figure 4.11. German Cockroaches, Various Stages and Ages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5

Figure 4.12. Brown-banded Cockroaches, Various Stages and Ages . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5

Figure 4.13. Wood Cockroach, Adult Male . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5

Figure 4.14. Reported Human Plague Cases (1970–1997) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6

Figure 4.15. Flea Life Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6

Figure 4.16. Housefly (Musca domestica) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-7

Figure 4.17. Life Cycle of the Fly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-8

Figure 4.18. Termite Tube Extending From Ground to Wall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-9

Figure 4.19. Termite Mud Shelter Tube Constructed Over A Brick Foundation . . . . . . . . . . . . . . . . . . . .4-9

Figure 4.20. Differences Between Ants and Termites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-9

Figure 4.21. Life Cycle of the Subterranean Termite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-10

Figure 4.22. Subterranean Termite Risk in the United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-11

Figure 4.23. Typical Points of Attack by Termites in the Home . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-12

Figure 4.24. Construction Techniques That Discourage Termite Attacks . . . . . . . . . . . . . . . . . . . . . . . . . .4-14

Figure 4.25. Fire Ants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-14

Figure 4.26. Range Expansion of Red Imported Fire Ants (RIFA) in the United States, 1918–1998 . . . . .4-15

Figure 4.27. Fire Ant Mound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-15

Healthy Housing Reference Manual 1

Contents
“Sometimes poor housing is a shorthand way of describing

living conditions of poor people. The poor include the aged,

deprived, ethnic minority groups, the infirmed, and families

headed by unemployed women. In other words, the people

most at risk for illness often live in inferior housing.

Therefore, it is a matter of conjecture whether many people

live in poor housing because they are sick or are sick because

they live in poor housing.”

Carter L. Marshall, M.D.

Dynamics of Health and Disease 

Appleton, Century Crofts 1972

Introduction

The most immediate and obvious link between housing and

health involves exposure to biologic, chemical, and

physical agents that can affect the health and safety of the

occupants of the home. Conditions such as childhood lead

poisoning and respiratory illnesses caused by exposure to

radon, asbestos, tobacco smoke, and other pollutants are

increasingly well understood and documented. However,

even 50 years ago, public health officials understood that

housing conditions were linked to a broader pattern of

community health. For example, in 1949, the Surgeon

General released a report comparing several health status

indicators among six cities having slums. The publication

reported that: 

• the rate of deaths from communicable disease in

these areas was the same as it was for the rest of

the country 50 years ago (i.e., around 1900);

• most of the tuberculosis cases came from 25% of

the population of these cities; and

• the infant mortality rate was five times higher

than in the rest of the country, approximately

equal to what it was 50 years ago.

Housing-related health concerns include asthma episodes

triggered by exposure to dust mites, cockroaches, pets,

and rodents. The existence of cockroaches, rats, and mice

mean that they can also be vectors for significant

problems that affect health and well-being. They are

capable of transmitting diseases to humans. According to

a 1997 American Housing Survey, rats and mice infested

2.7 million of 97 million housing units. A CDC-sponsored

survey of two major American cities documented that

nearly 50% of the premises were infected with rats and mice. 

This chapter deals with disease vectors and pests as

factors related to the health of households.

Disease Vectors and Pests 

Integrated pest management (IPM) techniques are

necessary to reduce the number of pests that threaten

human health and property. This systems approach to

the problem relies on more than one technique to reduce

or eliminate pests. It can be visualized best as concentric

rings of protection that reduce the need for the most

risky and dangerous options of control and the potential

for pests to evolve and develop. It typically involves using

some or all of the following steps:

• monitoring, identifying, and determining the

level of threat from pests;

• making the environment hostile to pests;

• building the pests out by using pest-proof building

materials;

• eliminating food sources, hiding areas, and

other pest attractants;

• using traps and other physical elimination devices; and 

• when necessary, selecting appropriate poisons

for identified pests.

The above actions are discussed in more detail in the

following section on the four basic strategies for

controlling rodents. 

Most homeowners have encountered a problem with

rodents, cockroaches, fleas, flies, termites, or fire ants.

These pests destroy property or carry disease, or both,

and can be a problem for rich and poor alike. 

Rodents

Rodents destroy property, spread disease, compete for human

food sources, and are aesthetically displeasing. Rodentassociated diseases affecting humans include plague, murine

typhus, leptospirosis, rickettsialpox, and rat-bite fever. The

three primary rodents of concern to the homeowner are the

Norway rat (Rattus norvegicus), roof rat (Rattus rattus), and the

house mouse (Mus musculus). The term “commensal” is

applied to these rodents, meaning they live at people’s expense.

The physical traits of each are demonstrated in Figure 4.1. 

Chapter 4: Disease Vectors and Pests

Healthy Housing Reference Manual 4-1
Barnett [1] notes that the house mouse is abundant

throughout the United States. The Norway rat

(Figure 4.2) is found throughout the temperate regions

of the world, including the United States. The roof rat

is found mainly in the South, across the entire nation to

the Pacific coast. As a group, rodents have certain

behavioral characteristics that are helpful in

understanding them. They are perceptive to touch,

with sensitive whiskers and guard hairs on their bodies.

Thus, they favor running along walls and between

objects that allow them

constant contact with

vertical surfaces. They are

known to have poor

eyesight and are alleged to

be colorblind.

Contrastingly, they have an

extremely sharp sense of

smell and a keen sense of

taste. The word rodent is

derived from the Latin verb

rodere, meaning “to gnaw.” 

The gnawing tendency leads to structural damage to

buildings and initiates fires when insulation is chewed

from electrical wires. Rodents will gnaw to gain entrance

and to obtain food.

The roof rat (Figure 4.3) is a slender, graceful, and very

agile climber. The roof rat prefers to live aboveground:

indoors in attics, between floors, in walls, or in enclosed

spaces; and outdoors in trees and dense vine growth.

Contrasted with the

roof rat, the Norway rat

is at home below the

ground, living in a

burrow. The house

mouse commonly is

found living in human

quarters, as suggested by

its name. Signs indicative

of the presence of

rodents—aside from seeing live or dead rats and hearing

rats—are rodent droppings, runways, and tracks

(Figure 4.4). Other signs include nests, gnawings, food

scraps, rat hair, urine spots, and rat body odors. Note

that waste droppings from rodents are often confused

with cockroach egg packets, which are smooth,

segmented, and considerably smaller than a mouse dropping.

According to the Military Pest Management Handbook

(MPMH) [2], rats and mice are very suspicious of any

new objects or food found in their surroundings. This

characteristic is one reason rodents can survive in dangerous

environments. This avoidance reaction accounts for

prebaiting (baiting without poisoning) in control programs.

4-2 Disease Vectors and Pests

Figure 4.1. Field Identification of Domestic Rodents [2]

Figure 4.2. Norway Rat [3]

Figure 4.3. Roof Rat [4]
Initially, rats or mice begin by taking only small amounts

of food. If the animal becomes ill from a sublethal dose of

poison, its avoidance reaction is strengthened, and a

poisoning program becomes extremely difficult to

complete. If rodents are hungry or exposed to an environment

where new objects and food are commonly found, such

as a dump, their avoidance reaction may not be as strong;

in extreme cases of hunger, it may even be absent. 

The first of four basic strategies for controlling rodents is

to eliminate food sources. To accomplish this, it is

imperative for the homeowner or occupant to do a good

job of solid waste management. This requires proper

storing, collecting, and disposing of refuse. 

The second strategy is to eliminate breeding and nesting

places. This is accomplished by removing rubbish from

near the home, including excess lumber, firewood, and

similar materials. These items should be stored above

ground with 18 inches of clearance below them. This

height does not provide a habitat for rats, which have a

propensity for dark, moist places in which to burrow.

Wood should not be stored directly on the ground, and

trash and similar rubbish should be eliminated.

The third strategy is to construct buildings and other

structures using rat-proofing methods. MPMH notes

that it is much easier to manage rodents if a structure is

built or modified in a way that prevents easy access by

rodents. Tactics for rodent exclusion include building or

covering doors and windows with metal. Rats can gnaw

through wooden doors and windows in a very short time

to gain entrance. All holes in a building’s exterior should

be sealed. Rats are capable of enlarging openings in

masonry, especially if the mortar or brick is of poor

quality. All openings more than 3⁄4-inch wide should be

closed, especially around pipes and conduits. Cracks

around doors, gratings, windows, and other such

openings should be covered if they are less than 4 feet

above the ground or accessible from ledges, pipes, or

wires (Figure 4.5). 

Additional tactics include using proper materials for rat

proofing. For example, sheet metal of at least 26-gauge,

1⁄4-inch or 1⁄2-inch hardware cloth, and cement are all

suitable rat-resistant materials. However, 1⁄2-inch

hardware cloth has little value against house mice. Tight

fittings and self-closing doors should be constructed.

Rodent runways can be behind double walls; therefore,

spaces between walls and floor-supporting beams should

be blocked with fire stops. A proper rodent-proofing

strategy must bear in mind that rats can routinely jump

2 feet vertically, dig 4 feet or more to get under a

foundation, climb rough walls or smooth pipes up to

3 inches in diameter, and routinely travel on electric

or telephone wires. 

The first three strategies—good sanitation techniques,

habitat denial, and rat proofing—should be used initially

in any rodent management program. Should they fail, the

fourth strategy is a killing program, which can vary from

a family cat to the professional application of

rodenticides. Cats can be effective against mice, but

typically are not useful against a rat infestation. Over-thecounter rodenticides can be purchased and used by the

homeowner or occupant. These typically are in the red

squill or warfarin groups. 

A more effective alternative is trapping. There are a

variety of devices to choose from when trapping rats or

mice. The two main groups of rat and mouse traps are

live traps (Figure 4.6) and kill traps (Figure 4.7). Traps

usually are placed along walls, near runways and burrows,

and in other areas. Bait is often used to attract the

rodents to the trap. To be effective, traps must be

monitored and emptied or removed quickly. If a rat

caught in a trap is left there, other rats may avoid the traps.

A trapping strategy also may include using live traps to

remove these vermin. 

Healthy Housing Reference Manual 4-3

Figure 4.4. Signs of Rodent Infestation [2]
Cockroaches 

Cockroaches have become well adapted to living with and

near humans, and their hardiness is legendary. In light of

these facts, cockroach control may become a homeowner’s

most difficult task because of the time and special

knowledge it often involves. The cockroach is considered

an allergen source and an asthma trigger for residents.

Although little evidence exists to link the cockroach to

specific disease outbreaks, it has bee demonstrated to

carry Salmonella typhimurium, Entamoeba histolytica, and

the poliomyelitis virus. In addition, Kamble and Keith [6]

note that most cockroaches produce a repulsive odor that

can be detected in infested areas. The sight of cockroaches

can cause considerable psychologic or emotional distress

in some individuals. They do not bite, but they do have

heavy leg spines that may scratch. 

According to MPMH [2], there are 55 species of

cockroaches in the United States. As a group, they tend to

prefer a moist, warm habitat because most are tropical in

origin. Although some tropical cockroaches feed only on

vegetation, cockroaches of public health interest tend to

live in structures and are customarily scavengers.

Cockroaches will eat a great variety of materials, including

cheese and bakery products, but they are especially fond

of starchy materials, sweet substances, and meat products. 

Cockroaches are primarily nocturnal. Daytime sightings

may indicate potentially heavy infestations. They tend to

hide in cracks and crevices and can move freely from

room to room or adjoining housing units via wall spaces,

plumbing, and other utility installations. Entry into

homes is often accomplished through food and beverage

boxes, grocery sacks, animal food, and household goods

carried into the home. The species of public health

Figure 4.7. Kill Traps for Rats [2]

Figure 4.5. Rodent Prevention [2]

Figure 4.6. Live Traps for Rats [5]

4-4 Disease Vectors and Pests
interest that commonly inhabit human dwellings

(Figures 4.8–4.13) include the following: German

cockroach (Blattella germanica); American cockroach

(Periplaneta americana); Oriental cockroach (Blatta

orientalis); brown-banded cockroach (Supella longipalpa);

Australian cockroach (Periplaneta australasiae); smokybrown cockroach (Periplaneta fuliginosa); and brown

cockroach (Periplaneta brunnea).

Four management strategies exist for controlling

cockroaches. The first is prevention. This strategy

includes inspecting items being carried into the home

and sealing cracks and crevices in kitchens, bathrooms,

exterior doors, and windows. Structural modifications

would include weather stripping and pipe collars. The

second strategy is sanitation. This denies cockroaches food,

water, and shelter. These efforts include quickly cleaning

food particles from shelving and floors; timely washing of

dinnerware; and routine cleaning under refrigerators,

stoves, furniture, and similar areas. If pets are fed indoors,

pet food should be stored in tight containers and not left

in bowls overnight. Litter boxes should be cleaned

routinely. Access should be denied to water sources by

fixing leaking plumbing, drains, sink traps, and purging

clutter, such as papers and soiled clothing and rags. The

third strategy is trapping. Commercially available cockroach

Figure 4.8. American, Oriental, German, and Brown- banded

Cockroaches [7]

Figure 4.9. American Cockroaches, Various Stages and Ages [7]

Figure 4.10. Oriental Cockroaches, Various Stages and Ages [7]

Figure 4.11. German Cockroaches, Various Stages and Ages [7]

Figure 4.12. Brown-banded Cockroaches, Various Stages and

Ages [7]

Figure 4.13. Wood Cockroach, Adult Male [7]

Healthy Housing Reference Manual 4-5
traps can be used to capture roaches and serve as a

monitoring device. The most effective trap placement is

against vertical surfaces, primarily corners, and under

sinks, in cabinets, basements, and floor drains. The fourth

strategy is chemical control. The use of chemicals

typically indicates that the other three strategies have been

applied incorrectly. Numerous insecticides are available

and appropriate information is obtainable from EPA. 

Fleas

The most important fleas as disease vectors are those that

carry murine typhus and bubonic plague. In addition,

fleas serve as intermediate hosts for some species of dog and

rodent tapeworms that occasionally infest people. They also

may act as intermediate hosts of filarial worms

(heartworms) in dogs. In the United States, the most

important disease related to fleas is the bubonic plague.

This is primarily a concern of residents in the southwestern

and western parts of the country (Figure 4.14). 

Of approximately 2,000 species of flea, the most common

flea infesting both dogs and cats is the cat flea

Ctenocephalides felis. Although numerous animals, both

wild and domestic, can have flea infestations, it is from

the exposure of domestic dogs and cats that most

homeowners inherit flea infestation problems. According to

MPMH [2], fleas are wingless insects varying from 1 to

81⁄2 millimeters (mm) long, averaging 2 to 4 mm, and

feed through a siphon or tube. They are narrow and

compressed laterally with backwardly directed spines,

which adapt them for moving between the hairs and

feathers of mammals and birds. They have long, powerful

legs adapted for jumping. Both sexes feed on blood, and

the female requires a blood meal before she can produce

viable eggs. Fleas tend to be host-specific, thus feeding on

only one type of host. However, they will infest other

species in the absence of the favored host. They are found

in relative abundance on animals that live in burrows and

sheltered nests, while mammals and birds with no

permanent nests or that are exposed to the elements tend

to have light infestations. 

MPMH [2] notes that fleas undergo complete metamorphosis

(egg, larva, pupa, and adult). The time it takes to

complete the life cycle from egg to adult varies according

to the species, temperature, humidity, and food

availability. Under favorable conditions, some species can

complete a generation in as little as 2 or 3 weeks.

Figure 4.15 shows the life cycle of the flea. 

4-6 Disease Vectors and Pests

Figure 4.14. Reported Human Plague Cases (1970–1997) [8]

Figure 4.15. Flea Life Cycle [2]
Flea eggs usually are laid singly or in small groups among

the feathers or hairs of the host or in a nest. They are

often laid in carpets of living quarters if the primary host

is a household pet. Eggs are smooth, spherical to oval,

light colored, and large enough to be seen with the naked 

eye. An adult female flea can produce up to 2,000 eggs in

a lifetime. Flea larvae are small (2 to 5 mm), white, and

wormlike with a darker head and a body that will appear

brown if they have fed on flea feces. This stage is mobile

and will move away from light, thus they typically will be

found in shaded areas or under furniture. In 5 to 12 days,

they complete the three larval stages; however, this may

take several months depending on environmental

conditions. The larvae, after completing development,

spin a cocoon of silk encrusted with granules of sand or

various types of debris to form the pupal stage. The pupal

stage can be dormant for 140 to 170 days. In some areas

of the country, fleas can survive through the winter. The

pupae, after development, are stimulated to emerge as

adults by movement, pressure, or heat. The pupal form of

the flea is resistant to insecticides. An initial treatment,

while killing egg, larvae, and adult forms, will not kill the

pupae. Therefore, a reapplication will often be necessary.

The adult forms are usually ready to feed about 24 hours

after they emerge from the cocoon and will begin to feed

within 10 seconds of landing on a host. Mating usually

follows the initial blood meal, and egg production is

initiated 24 to 48 hours after consuming a blood meal.

The adult flea lives approximately 100 days, depending

on environmental conditions.

Following are some guidelines for controlling fleas:

• The most important principle in a total flea control

program is simultaneously treating all pets and their

environments (indoor and outdoor).

• Before using insecticides, thoroughly clean the

environment, removing as many fleas as possible,

regardless of the form. This would include indoor

vacuuming and carpet steam cleaning. Special

attention should be paid to source points where pets

spend most of their time.

• Outdoor cleanup should include mowing, yard raking,

and removing organic debris from flowerbeds and

under bushes.

• Insecticide should be applied to the indoor and

outdoor environments and to the pet.

• Reapplication to heavily infested source points in

the home and the yard may be needed to eliminate pre-emerged adults.

Flies

The historical attitude of Western society toward flies has

been one of aesthetic disdain. The public health view is to

classify flies as biting or nonbiting. Biting flies include

sand flies, horseflies, and deerflies. Nonbiting flies include

houseflies, bottleflies, and screwworm flies. The latter

group is often referred to as synanthropic because of their

close association with humans. In general, the presence of

flies is a sign of poor sanitation. The primary concern of

most homeowners is nonbiting flies. 

According to

MPMH [2], the

housefly (Musca

domestica) (Figure

4.16) is one of the

most widely

distributed insects,

occurring

throughout the

United States, and

is usually the

predominant fly species in homes and restaurants. M.

domestica is also the most prominent human-associated

(synanthropic) fly in the southern United States. Because

of its close association with people, its abundance, and its

ability to transmit disease, it is considered a greater threat

to human welfare than any other species of nonbiting fly.

Each housefly can easily carry more than 1 million bacteria

on its body. Some of the disease-causing agents transmitted

by houseflies to humans are Shigella spp. (dysentery and

diarrhea = shigellosis), Salmonella spp. (typhoid fever),

Escherichia coli, (traveler’s diarrhea), and Vibrio cholera

(cholera). Sometimes these organisms are carried on the

fly’s tarsi or body hairs, and frequently they are

regurgitated onto food when the fly attempts to liquefy it

for ingestion. 

The fly life cycle is similar across the synanthropic group.

MPMH [2] notes that the egg and larval stages develop in

animal and vegetable refuse. Favorite breeding sites

include garbage, animal manure, spilled animal feed, and soil

contaminated with organic matter. Favorable

environmental conditions will result in the eggs hatching

in 24 hours or less. Normally, a female fly will produce

500 to 600 eggs during her lifetime. 

The creamy, white larvae (maggots) are about 1⁄2-inch

long when mature and move within the breeding material

Healthy Housing Reference Manual 4-7

Figure 4.16. Housefly [Musca domestica] [9]
to maintain optimum temperature and moisture

conditions. This stage lasts an average of 4 to 7 days in

warm weather. The larvae move to dry parts of the

breeding medium or move out of it onto the soil or

sheltered places under debris to pupate, with this stage

usually lasting 4 to 5 days. When the pupal stage is

accomplished, the adult fly exits the puparium, dries, hardens,

and flies away to feed, with mating occurring soon after

emergence. Figure 4.17 demonstrates the typical fly life

cycle. 

The control of the housefly is hinged on good sanitation

(denying food sources and breeding sites to the fly). This

includes the proper disposal of food wastes by placing

garbage in cans with close-fitting lids. Cans need to be

periodically washed and cleaned to remove food debris.

The disposal of garbage in properly operated sanitary

landfills is paramount to fly control. 

The presence of adult flies can be addressed in various

ways. Outside methods include limited placement of

common mercury vapor lamps that tend to attract flies.

Less-attractive sodium vapor lamps should be used near

the home. Self-closing doors in the home will deny

entrance, as will the use of proper-fitting and wellmaintained screening on doors and windows. 

Larger flies use homes for shelter from the cold, but do

not reproduce inside the home. Caulking entry points

and using fly swatters is effective and much safer than the

use of most pesticides. Insecticide “bombs” can be used in

attics and other rooms that can be isolated from the rest

of the house. However, these should be applied to areas

away from food, where flies rest. 

The blowfly is a fairly large, metallic green, gray, blue,

bronze, or black fly. They may spend the winter in homes

or other protected sites, but will not reproduce during

this time. Blowflies breed most commonly on decayed

carcasses (e.g., dead squirrels, rodents, birds) and in

droppings of dogs or other pets during the summer; thus,

removal of these sources is imperative. Small animals, on

occasion, may die inside walls or under the crawl space of

a house. A week or two later, blowflies or maggots may

appear. The adult blowfly is also attracted to gas leaks. 

Termites

According to Gold et al. [11], subterranean termites are

the most destructive insect pests of wood in the United

States, causing more than $2 billion in damage each year.

Annually, this is more property damage than that caused

by fire and windstorms combined. In the natural world,

these insects are beneficial because they break down dead

trees and other wood materials that would otherwise

accumulate. This biomass breakdown is recycled to the

soil as humus. MPMH [2], on the other hand, notes that

these insects can damage a building so severely it may

have to be replaced. Termites consume wood and other

cellulose products, such as paper, cardboard, and

fiberboard. They will also destroy structural timbers,

pallets, crates, furniture, and other wood products. In

addition, they will damage many materials they do not

normally eat as they search for food. The tunneling efforts

of subterranean termites can penetrate lead- and plasticcovered electric cable and cause electrical system failure.

In nature, termites may live for years in tree stumps or

lumber beneath concrete buildings before they penetrate

hairline cracks in floors and walls, as well as expansion

joints, to search for food in areas such as interior door

frames and immobile furniture. Termite management costs to

homeowners are exceeded only by cockroach control costs. 

Lyon [12] notes that termites are frequently mistaken by

the homeowner as ants and often are referred to

erroneously as white ants. Typical signs of termite

infestations occur in March through June and in

September and October. Swarming is an event where a

group of adult males and female reproductives leave the

nest to establish a new colony. If the emergence happens

inside a building, flying termites may constitute a

considerable nuisance. These pests can be collected with a

vacuum cleaner or otherwise disposed of without using

pesticides. Each homeowner should be aware of the

following signs of termite infestation:

• Pencil-thin mud tubes extending over the inside

and outside surfaces of foundation walls, piers,

sills, joists, and similar areas (Figures 4.18 and 4.19).

4-8 Disease Vectors and Pests

Figure 4.17. Life Cycle of the Fly [10]
• Presence of winged termites or their shed wings

on windowsills and along the edges of floors.

• Damaged wood hollowed out along the grain and

lined with bits of mud or soil. According to Oi

et al. [15], termite tubes and nests are made of

mud and carton. Carton is composed of partially

chewed wood, feces, and soil packed together.

Tubes maintain the high humidity required for

survival, protect termites from predators, and

allow termites to move from one spot to another. 

Differentiating the ant from the dark brown or black

termite reproductives can be accomplished by noting the

respective wings and body shape. MPMH [2] states that a

termite has four wings of about equal length and that the

wings are nearly twice as long as the body. By comparison, ant

wings that are only a little longer than the body and the

hind pair is much shorter than the front. Additionally,

ants typically have a narrow waist, with the abdomen

connected to the thorax by a thin petiole. Termites do

not have a narrow or pinched waist. Figure 4.20a and b

demonstrates the differences between the ant and termite.

Entomologists refer to winged ants and termites as alates. 

Figure 4.21 shows the life cycle of the termite. In each

colony, there are three castes or forms of individuals

known as reproductives, workers, and soldiers. According

to Lyon [12], the reproductives can be winged or

wingless, with the latter found in colonies to serve as

replacements for the primary reproductives. The primary

reproductives (alates) vary in color from pale yellowbrown to coal black, are 1⁄2-inch to 3/8-inch in length, are

flattened dorsa-ventrally, and have pale or smoke-gray to

brown wings. The secondary reproductives have short

wing buds and are white to cream colored. The workers

are the same size as the primary reproductives and are

white to grayish-white, with a yellow-brown head, and

are wingless. In addition, the soldiers resemble workers,

in that they are wingless, but soldiers have large,

rectangular, yellowish, and brown heads with large jaws.

MPMH [2] states there are five families of termites found

in the world, with four of them occurring in the United

States. The families in the United States are

Hodotermitidae (rotten-wood termites), Kalotermitidae

(dry-wood termites), Rhinotermitidae (subterranean

Healthy Housing Reference Manual 4-9

Figure 4.20a. Ant (Elbowed Antennae: Fore Wings Larger Than Hind;

Constricted Waist) [16]

Figure 4.20b. Termite (Beaded Antennae; All Wings Equal) [16]

Figure 4.18. Termite Tube Extending from Ground to Wall [Red

Arrows] [13]

Figure 4.19. Termite Mud Shelter Tube Constructed Over a Brick

Foundation [14]
termites) and Termitidae (desert termites). Subterranean

termites typically work in wood aboveground, but must

have direct contact with the ground to obtain moisture.

Nonsubterranean termites colonize above the ground and

feed on cellulose; however, their life cycles and methods

of attack, and consequently methods of control, are quite

different. Nonsubterranean termites in the United States

are commonly called drywood termites. 

In the United States, according to MPMH [2], native

subterranean termites are the most important and the

most common. These termites include the genus

Reticulitermes, occurring primarily in the continental

United States, and the genus Heterotermes, occurring in

the Virgin Islands, Puerto Rico, and the deserts of California

and Arizona. The appearance, habits, and type of damage

they cause are similar. The Formosan termite (Coptotermes

formosanus) is the newest species to become established in

the United States. It is a native of the Pacific Islands and

spread from Hawaii and Asia to the United States during

the 1960s. It is now found along the Gulf Coast, in

California, and in South Carolina, and is expected to

spread to other areas as well. Formosan termites cause

greater damage than do native species because of their

more vigorous and aggressive behavior and their ability to

rapidly reproduce, build tubes and tunnels, and seek out

new items to infest. They have also shown more resistance

to some soil pesticides than native species. Reproductives

(swarmers) are larger than native species, reaching up to

5/8-inch in length, and are yellow to brown in color.

Swarmers have hairy-looking wings and swarm after dusk,

unlike native species, which swarm in the daytime.

Formosan soldiers have more oval-shaped heads than do

native species. On top of the head is an opening that

emits a sticky, whitish substance.

Dry-wood termites (Cryptotermes spp.) live entirely in

moderately to extremely dry wood. They require contact

with neither the soil nor any other moisture source and

may invade isolated pieces of furniture, fence posts,

utility poles, firewood, and structures. Dry-wood termite

colonies are not as large as other species in the United

States, so they can occupy small wooden articles, which

are one way these insects spread to different locations.

They are of major economic importance in southern

California, Arizona, and along the Gulf Coast. The West

Indian dry-wood termite is a problem in Puerto Rico, the

U.S. Virgin Islands, Hawaii, parts of Florida and

Louisiana, and a number of U.S. Pacific Island territories.

Dry-wood termites are slightly larger than most other

species, ranging from 1⁄2 inch to 5/8 inch long, and are

generally lighter in color. 

Damp-wood termites do not need contact with damp

ground like subterranean termites do, but they do require

higher moisture content in wood. However, once

established, these termites may extend into slightly drier wood. 

Termites of minor importance are the tree-nesting groups.

The nests of these termites are found in trees, posts, and,

occasionally, buildings. Their aboveground nests are

connected to soil by tubes. Tree-nesting termites may be a

problem in Puerto Rico and the U.S. Virgin Islands. 

The risk for encountering subterranean termites in the

United States is greater in the southeastern states and in

southwestern California. In the United States, the risk for

termite infestations tends to decrease as the latitude

increases northward. 

Figure 4.22 portrays the geographic risk of subterranean

termites in the United States. Subterranean termites are

found in all states except Alaska and are most abundant

in the south and southeastern United States [18].

According to Potter [19], homeowners can reduce the risk

for termite attack by adhering to the following suggestions:

• Eliminate wood contact with the ground. Earthto-wood contact provides termites with

simultaneous access to food, moisture, and shelter

in conjunction with direct, hidden entry into the

structure. In addition, the homeowner or

occupant should be aware that pressure-treated

wood is not immune to termite attack because

termites can enter through the cut ends and build

tunnels over the surfaces.

4-10 Disease Vectors and Pests

Figure 4.21. Life Cycle of the Subterranean Termite [17]
• Do not allow moisture to accumulate near the

home’s foundation. Proper drainage, repair of

plumbing, and proper grading will help to reduce

the presence of moisture, which attracts termites.

• Reduce humidity in crawl spaces. Most building

codes state that crawl space area should be vented

at a rate of 1 square foot per 150 square feet of

crawl space area. This rate can be reduced for

crawl spaces equipped with a polyethylene or

equivalent vapor barrier to one square foot per

300 to 500 square feet of crawl space area. Vent

placement design includes positioning one vent

within 3 feet of each building corner. Trimming

and controlling shrubs so that they do not

obstruct the vents is imperative. Installling a 4-

to 6-mil polyethylene sheeting over a minimum of

75% of the crawl space will reduce the crawlspace moisture. Covering the entire floor of the

crawl space with such material can reduce two

potential home problems at one time: excess

moisture and radon (Chapter 5). The barrier will

reduce the absorption of moisture from the air

and the release of moisture into the air in the

crawl space from the underlying soil. 

• Never store firewood, lumber, or other wood debris

against the foundation or inside the crawl space.

Termites are both attracted to and fed by this type

of storage. Wood stacked in contact with a

dwelling and vines, trellises, and dense plant

material provide a pathway for termites to bypass

soil barrier treatment. 

• Use decorative wood chips and mulch sparingly.

Cellulose-containing products attract termites,

especially materials that have moisture-holding

properties, such as mulch. The homeowner should

never allow these products to contact wood

components of the home. The use of crushed

stone or pea gravel is recommended as being less

attractive to termites and helpful in diminishing

other pest problems.

• Have the structure treated by a professional pest

control treatment. The final, and most effective,

strategy to prevent infestation is to treat the soil

around and beneath the building with termiticide.

The treated ground is then both a repellant and

toxic to termites.

Healthy Housing Reference Manual 4-11

Figure 4.22. Subterranean Termite Risk in the United States [18]
Figure 4.23 demonstrates some typical points of attack by

subterranean termites and some faulty construction practices

that can contribute to subterranean termite infestations. 

Lyon [12] notes the following alternative termite control

measures:

• Nematodes. Certain species of parasitic round

worms (nematodes) will infest and kill termites

and other soil insects. Varying success has been

experienced with this method because it is

dependent on several variables, such as soil

moisture and soil type.

• Sand as a physical barrier. This would require

preconstruction planning and would depend on

termites being unable to manipulate the sand to

create tunnels. Some research in California and

Hawaii has indicated early success.

• Chemical baits. This method uses wood or

laminated texture-flavored cellulose impregnated

with a toxicant and/or insect growth regulator.

The worker termite feeds on the substance and

carries it back to the nest, reducing or eliminating

the entire colony. According to HomeReports.com

[20], an additional system is to strategically

place a series of baits around the house. The

intention is for termite colonies to encounter one

or more of the baits before approaching the

house. Once termite activity is observed, the bait

wood is replaced with a poison. The termites

bring the poison back to the colony and the

colony is either eliminated or substantially

reduced. This system is relatively new to the

market. Its success depends heavily on the

termites finding the bait before finding and

damaging the house.

Additional measures include construction techniques that

discourage termite attacks, as demonstrated in Figure 4.24.

Termites often invade homes by way of the foundation,

either by crawling up the exterior surface where their

activity is usually obvious or by traveling inside hollow

block masonry. One way to deter their activity is to block

their access points on or through the foundation. Metal

termite shields have been used for decades to deter

termite movement along foundation walls and piers on

up to the wooden structure. Metal termite shields should

extend 2 inches from the foundation and 2 inches down.

Improperly installed (i.e., not soldered/sealed properly),

damaged, or deteriorated termite shields may allow

Figure 4.23. Typical Points of Attack by Termites in the Home [2]

4-12 Disease Vectors and Pests
termites to reach parts of the wooden floor system.

Shields should be made of noncorroding metal and have

no cracks or gaps along the seams. If a house is being

built with metal termite shielding, the shielding should

extend at least 2 inches out and 2 inches down at a 45°

angle from the foundation wall. An alternative to using

termite shields on a hollow-block foundation is to fill the

block with concrete or put in a few courses of solid or

concrete-filled brick (which is often done anyway to level

foundations). These are referred to as masonry caps. The

same approach can be used with support piers in the

crawl space. Solid caps (i.e., a continuously poured

concrete cap) are best at stopping termites, but are not

commonly used. Concrete-filled brick caps should deter

termite movement or force them through small gaps, thus

allowing them to be spotted during an inspection [21]. 

Fire Ants

According to MPMH [2], ants are one of the most

numerous species on earth. Ants are in the same order as

wasps and bees and, because of their geographic

distribution, they are universally recognized (Figure 4.25).

The life cycle of the fire ant begins with the mating of the

winged forms (alates) some 300 to 800 feet in the air,

typically occurring in the late spring or early summer. The

male dies after the mating; and the newly mated queen

finds a suitable moist site, drops her wings, and burrows

in the soil, sealing the opening behind her. Ants undergo

complete metamorphosis and, therefore, have egg, larval,

pupal and adult stages. The new queen will begin laying

eggs within 24 hours. Once fully developed, she will

produce approximately 1,600 eggs per day over a

maximum life span of 7 years. Soft, whitish, legless larvae

are produced from the hatching. These larvae are fed by

the worker ants. Pupae resemble adults in form, but are

soft, nonpigmented, and lack mobility. There are at least

three distinct castes of ants: workers, queens, and males.

Typically, the males have wings, which they retain until

death. Queens, the largest of the three castes, normally

have wings, but lose them after mating. The worker,

which is also a female, is never winged, except as a rare

abnormality. Within this hierarchy, mature colonies

contain males and females that are capable of flight and

reproduction. These are known as reproductives, and an

Healthy Housing Reference Manual 4-13

1. Cracks in foundation permit hidden points of 

entry from soil to sill.

2. Posts through concrete in contact with 

substructural soil. Watch door frames and 

intermediate supporting posts.

3. Wood-framing members in contact with 

earthfill under concrete slab.

4. Form boards left in place contribute to 

termite food supply.

5. Leaking pipes and dripping faucets sustain soil 

moisture. Excess irrigation has same effect.

6. Shrubbery blocking air flow through vents.

7. Debris supports termite colony until large 

population attacks superstructure.

8. Heating unit accelerates termite development 

by maintaining warmth of colony on a yearround basis.

9. Foundation wall too low permits wood to 

contact soil. Adding topsoil often builds exterior 

grade up to sill level.

10. Footing too low or soil thrown against it causes 

wood-soil contact. There should be 8 inches 

of clean concrete between soil and pier block.

11. Stucco carried down over concrete foundation 

permits hidden entrance between stucco and 

foundation if bond fails.

12. Insufficient clearance for inspection also 

permits easy construction of termite shelter tubes 

from soil to wood.

13. Wood framing of crawl hole forming 

wood-soil contact.

14. Mud sill and/or posts in contact with soil.

15. Wood siding and skirting form soil contact. 

There should be a minimum of 3 inches 

clearance between skirting and soil.

16. Porch steps in contact with soil. Also watch for 

ladders and other wooden materials.

17. Downspouts should carry water away from

the building.

18. Improper maintenance of soil piled against pier 

footing. Also makes careful inspection impossible.

19. Wall girder entering recess and foundation wall.

Should have a 1-inch free air space on both 

sides and end and be protected with a moistureimpervious seal.

20. Vents placed between joists tunnel air through 

space without providing good substructural 

aeration. Vents placed in foundation wall give 

better air circulation.

Key to Figure 4.23
average colony may produce approximately 4,500 of these

per year. A healthy nest usually produces two nuptial

flights of reproductives each year and a healthy, mature

colony may contain more than 250,000 ants. Though

uncommon among ants, multiple queen colonies (10 to

100) occur somewhat frequently in fire ants, resulting in

more numerous mounds per acre.

There are many species of fire ants in the United States.

The most important are four species in the genus

Solenopsis. Of these, the number one fire ant pest is the

red imported fire ant (RIFA) Solenopsis invicta

(Figure 4.25). This ant was imported inadvertently from

South America in the 1930s through the port of Mobile,

Alabama. RIFAs are now found in more than 275 million

acres in 11 southern states and Puerto Rico. The second

most important species is the black imported fire ant,

S. richteri, which was introduced into the United States 

in the 1920s from Argentina or Uruguay. It is currently

limited in distribution to a small area of northern

Mississippi and Alabama. There are two native species

of fire ants: the tropical or native fire ant, S. geminata,

ranging from South Carolina to Florida and west to

Texas; and the Southern fire ant, S. xyloni, which occurs

from North Carolina south to northern Florida, along the

Gulf Coast, and west to California. The most important

extension of the RIFA range is thought to have occurred

during the 1950s housing boom as a result of the

transportation of sod and nursery plants (Figure 4.26).

RIFAs prefer open and sun-exposed areas. They are found

in cultivated fields, cemeteries, parks, and yards, and even

inside cars, trucks, and recreational vehicles. RIFAs are

attracted to electrical currents and are known to nest in

and around heat pumps, junction boxes, and similar

areas. They are omnivorous; thus they will attack most

things, living or dead. Their economic effects are felt by

their destruction of the seeds, fruit, shoots, and seedlings

of numerous native plant species. Fire ants are known to

tend pests, such as scale insects, mealy bugs, and aphids,

for feeding on their sweet waste excretion (honeydew).

RIFAs transport these insects to new feeding sites and

protect them from predators. The positive side of RIFA

infestation is that the fire ant is a predator of ticks and

controls the ground stage of horn flies.

4-14 Disease Vectors and Pests

Figure 4.24. Construction Techniques That Discourage Termite Attacks: Thin Metal Termite Shield Should Extend 2 Inches Beyond Foundation and 2 Inches

Down [2]

Figure 4.25. Fire Ants [22]
The urban dweller with a RIFA infestation may find

significant damage to landscape plants, with reductions in

the number of wild birds and mammals. RIFAs can

discourage outdoor activities and be a threat to young

animals or small confined pets. RIFA nests typically are

not found indoors, but around homes, roadways, and

structures, as well as under sidewalks. Shifting of soil after

RIFAs abandon sites has resulted in collapsing structures.

Figure 4.27 shows a fire ant mound with fire ants and a

measure of their relative size. 

The medical complications of fire ant stings have been

noted in the literature since 1957. People with disabilities,

reduced feeling in their feet and legs, young children, and

those with mobility issues are at risk for sustaining

numerous stings before escaping or receiving assistance.

Fatalities have resulted from attacks on the elderly and on

infants. Control of the fire ant is primarily focused on the

mound by using attractant bait consisting 

of soybean oil, corn grits, or chemical agents. The bait is

picked up by the worker ants and taken deep into the

mound to the queen. These products typically require

weeks to work. 

Individual mound treatment is usually most effective in

the spring. The key is to locate and treat all mounds in

the area to be protected. If young mounds are missed, the

area can become reinfested in less than a year. 

Mosquitoes 

All mosquitoes have four stages of development—egg,

larva, pupa, and adult—and spend their larval and pupal

stages in water. The females of some mosquito species

deposit eggs on moist surfaces, such as mud or fallen

leaves, that may be near water but dry. Later, rain or high

tides reflood these surfaces and stimulate the eggs to

hatch into larvae. The females of other species deposit

their eggs directly on the surface of still water in such

places as ditches, street catch basins, tire tracks, streams

that are drying up, and fields or excavations that hold

water for some time. This water is often stagnant and

close to the home in discarded tires, ornamental pools,

Healthy Housing Reference Manual 4-15

Figure 4.26. Range Expansion of Red Imported Fire Ants [RIFAs] in the United States, 1918–1998 [23]

Figure 4.27. Fire Ant Mound

Source: CAPT Craig Shepherd, U.S. PHS; used with permission.
unused wading and swimming pools, tin cans, bird baths,

plant saucers, and even gutters and flat roofs. The eggs

soon hatch into larvae. In the hot summer months, larvae

grow rapidly, become pupae, and emerge 1 week later as

flying adult mosquitoes. A few important spring species

have only one generation per year. However, most species

have many generations per year, and their rapid increase

in numbers becomes a problem.

When adult mosquitoes emerge from the aquatic stages,

they mate, and the female seeks a blood meal to obtain

the protein necessary for the development of her eggs.

The females of a few species may produce a first batch of

eggs without this first blood meal. After a blood meal is

digested and the eggs are laid, the female mosquito again

seeks a blood meal to produce a second batch of eggs.

Depending on her stamina and the weather, she may

repeat this process many times without mating again. The

male mosquito does not take a blood meal, but may feed

on plant nectar. He lives for only a short time after

mating. Most mosquito species survive the winter, or

overwinter, in the egg stage, awaiting the spring thaw,

when waters warm and the eggs hatch. A few important

species spend the winter as adult, mated females, resting

in protected, cool locations, such as cellars, sewers, crawl

spaces, and well pits. With warm spring days, these

females seek a blood meal and begin the cycle again.

Only a few species can overwinter as larvae.

Mosquitoborne diseases, such as malaria and yellow fever,

have plagued civilization for thousands of years. Newer threats

include Lyme disease and West Nile virus. Organized mosquito

control in the United States has greatly reduced the

incidence of these diseases. However, mosquitoes can still

transmit a few diseases, including eastern equine encephalitis

and St. Louis encephalitis. The frequency and extent of

these diseases depend on a complex series of factors.

Mosquito control agencies and health departments cooperate

in being aware of these factors and reducing the chance

for disease. It is important to recognize that young adult

female mosquitoes taking their first blood meal do not

transmit diseases. It is instead the older females, who, if they

have picked up a disease organism in their first blood meals,

can then transmit the disease during the second blood meal. 

The proper method to manage the mosquito problem in

a community is through an organized integrated pest

management system that includes all approaches that safely

manage the problem. The spraying of toxic agents is but

one of many approaches.

When mosquitoes are numerous and interfere with living,

recreation, and work, you can use the various measures

described in the following paragraphs to reduce their

annoyance, depending on location and conditions.

How to Reduce the Mosquito Population

The most efficient method of controlling mosquitoes is

by reducing the availability of water suitable for larval

and pupal growth. Large lakes, ponds, and streams that have

waves, contain mosquito-eating fish, and lack aquatic

vegetation around their edges do not contain mosquitoes;

mosquitoes thrive in smaller bodies of water in protected

places. Examine your home and neighborhood and take the

following precautions recommended by the New Jersey

Agricultural Experiment Station [24]:

• dispose of unwanted tin cans and tires; 

• clean clogged roof gutters and drain flat roofs; 

• turn over unused wading pools and other

containers that tend to collect rainwater;

• change water in birdbaths, fountains, and troughs

twice a week; 

• clean and chlorinate swimming pools; 

• cover containers tightly with window screen or

plastic when storing rainwater for garden use

during drought periods; 

• flush sump-pump pits weekly; and 

• stock ornamental pools with fish.

If mosquito breeding is extensive in areas such as woodland

pools or roadside ditches, the problem may be too great

for individual residents. In such cases, call the organized

mosquito control agency in your area. These agencies

have highly trained personnel who can deal with the

problem effectively.

Several commercially available insecticides can be effective

in controlling larval and adult mosquitoes. These chemicals

are considered sufficiently safe for use by the public.

Select a product whose label states that the material is

effective against mosquito larvae or adults. For safe and

effective use, read the label and follow the instructions for

applying the material. The label lists those insects that the

EPA agrees are effectively controlled by the product. 

4-16 Disease Vectors and Pests
For use against adult mosquitoes, some liquid insecticides

can be mixed according to direction and sprayed lightly

on building foundations, hedges, low shrubbery, ground

covers, and grasses. Do not overapply liquid insecticides—

excess spray drips from the sprayed surfaces to the ground,

where it is ineffective. The purpose of such sprays is to

leave a fine deposit of insecticide on surfaces where mosquitoes

rest. Such sprays are not effective for more than 1 or 2 days.

Some insecticides are available as premixed products or

aerosol cans. These devices spray the insecticide as very

small aerosol droplets that remain floating in the air and

hit the flying mosquitoes. Apply the sprays upwind, so

the droplets drift through the area where mosquito

control is desired. Rather than applying too much of

these aerosols initially, it is more practical to apply them

briefly but periodically, thereby eliminating those

mosquitoes that recently flew into the area.

Various commercially available repellents can be

purchased as a cream or lotion or in pressurized cans, then

applied to the skin and clothing. Some manufacturers also

offer clothing impregnated with repellents; coarse,

repellent-bearing particles to be scattered on the ground;

and candles whose wicks can be lit to release a repellent

chemical. The effectiveness of all repellents varies from

location to location, from person to person, and from

mosquito to mosquito. Repellents can be especially

effective in recreation areas, where mosquito control may

not be conducted. All repellents should be used according

to the manufacturers’ instructions. Mosquitoes are

attracted by perspiration, warmth, body odor, carbon

dioxide, and light. Mosquito control agencies use some of

these attractants to help determine the relative number of

adult mosquitoes in an area. Several devices are sold that

are supposed to attract, trap, and destroy mosquitoes and

other flying insects. However, if these devices are

attractive to mosquitoes, they probably attract more

mosquitoes into the area and may, therefore, increase

rather than decrease mosquito annoyance.

References 

1. Barnett DB. Vectors and their control. In: Morgan

MT, editor. Environmental health. 3rd ed.

Englewood, CO: Wadsworth Publishing Co.;

2002. p. 137–50.

2. Armed Forces Pest Management Board. Military

pest management handbook. Washington, DC:

Armed Forces Pest Management Board; no date.

Available from URL: http://www.afpmb.org/

MPMH/toc.htm. 

3. Indiana Department of Natural Resources.

Rodent pictures. Lafayette, IN: Indiana

Department of Natural Resources; no date.

Available from URL: http://www.entm.purdue.edu/

wildlife/rat_pictures.htm.

4. Arrow Services, Inc. Rats: roof rats. Plymouth,

IN: Arrow Services, Inc.; no date. Available from

URL: http://www.arrowpestcontrol.com/

pages/rod/roofpic.html.

5. Cobb County Extension Service. Fact sheet on

rodents: rats and mice. Marietta, GA: Cobb

County Extension Service; 2003. Available from

URL: http://www.griffin.peachnet.edu/ga/cobb/

Horticulture/Factsheets/peskycritters/ratsmice.htm.

6. Kamble ST, Keith DL. Cockroaches and their

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4-18 Disease Vectors and Pests