State University Extension
Home Maintenance And Repair - 01500526
Cockroaches, also known as waterbugs and palmettobugs, are among the
most difficult household pests to control. Except for periods of warm
weather when they may migrate from house to house, domestic cockroaches
in Michigan spend their entire life inside buildings. Usually they are
found in basements, bathrooms and kitchens where they feed upon a wide
variety of foods, including cereals, sugar-containing foods, meats,
cheese, beer and soda pop, as well as leather, bookbindings, and
wallpaper paste. They can be carried into homes in cardboard cartons,
sacks, beverage containers, furniture and pet foods.
Cockroaches have long been companions of man. The old Romans called
them "lucifuga" because of their habit of running away from light. Most
cockroach species are active at night and hide in dark areas during the
day. The word cockroach no doubt can be traced to the Spanish word
Cockroaches are one of the most disagreeable insects that may invade
homes. While it is not true that an unkept home will cause a roach
infestation, there is indeed a strong correlation between sanitation
and cockroach populations once an infestation gets started. The
presence of roaches often causes serious mental anguish for some
homeowners. Roaches often associate themselves with filth and are known
to be involved in the spread of bacterial organisms which cause
gastroenteritis and other intestinal infections. Some people are
allergic to cockroach secretions and cuticular proteins. Cockroach body
fluids contain an allergen which causes an allergic reaction when there
is contact with live roaches, roach "byproducts" (fecal material and
body parts) or contaminated food and utensils. There is also a foul
smelling, oily liquid that is produced by most roach species; this oily
liquid is known to stain fabrics, woodwork and other surfaces.
The exact origin of our domestic species is disputed, but many are
tropical forms and now are widely distributed throughout the world by
commerce. In our area, we are commonly bothered by five different
species of cockroaches. Four of these are domestic roaches, while the
fifth is more at home outdoors but also gets into the house.
The American cockroach, our largest, may grow to 1 1/2 inches (35 mm).
It is reddish-brown or mahogany with light markings on top of the
thorax (the body division that bears the winds and legs) and matures in
about seven months. The adults may live for up to 18 months. The nymph
are grayish-brown, becoming reddish-brown as they mature, and wingless.
It prefers damp areas such as basements, and may be found around pipes,
sewage systems, and drainage systems in homes, commercial buildings and
The Oriental cockroach is Black, 1 1/4 inches (30 mm) long when
full-grown and has short wings, the wings of the female being only
rudimentary. It may take as long as 22 months to mature, and is a
relatively sluggish insect. Living on filth, it travels along sewage
systems into homes. This species will migrate outside from building to
building and enter buildings through ventilators, broken foundations,
and under poorly fitted doors. It prefers damp, cool areas, especially
basements and crawl spaces and near drains and leaky water pipes. They
can be found under sinks, refrigerators and washing machines if those
areas are damp. Outdoors they can be found beneath decaying leaves and
stones, and in mulch, garbage piles and water-meter vaults.
The German cockroach is smaller, slightly over 1/2 inch (12-15 mm)
long, brownish-tan with two black parallel lines just behind the head.
The nymphs are darker, wingless, and also have two lengthwise stripes
behind the head. This species prefers high relative humidity and warmth
and is a significant pest problem in homes, restaurants, hotels, food
plants, warehouses, dumps, office buildings, hospitals, ship and retail
stores. It is quite active and can easily migrate throughout buildings
thus becoming a major pest in apartment buildings. This roach prefers a
kitchen or bathroom where there is plenty of food, moisture and hiding
places, but they can often be found in other parts of the house as
well. This species produces more eggs and has more generations per year
(3 or 4) than other cockroaches; thus, a troublesome infestation can
develop rapidly after the chance introduction of just a few
The brown-banded cockroach is a fairly recent introduction first found
in Florida in 1903. It has since spread through the South and into some
areas of the northern U.S., being fairly common in Michigan. While it
normally congregates, individuals can wander throughout the house,
hiding in furniture, bookcases, television sets, radios, computers,
light switches, behind pictures hung on the wall, and closets or other
secluded locations, especially those high off the floor. It is slightly
under 1/2 inch (10-12 mm) when mature, and is colored a straw brown.
Two brownish bands are located on the wings of the adult, one where the
wings join the body, and one a little further back toward the wing
tips. The term "brown-banded", however, describes the immature form
more accurately than the adult, since the bands are conspicuous on the
abdomens of the nymphs. The species prefers temperatures over 80
degrees F, and takes up to 150 days to mature at this temperature.
Another roach sometimes found invading the home in the spring is the
Pennsylvania wood roach. This species lives outdoors and is not as fast
nor wary as its house- dwelling relatives. They may wander into
buildings in wooded areas, or may be brought into the house under the
bark of fireplace wood (they are common in woodpiles), and can exist in
the house living on food in the kitchen. The males of this species have
long wings and may fly for short distances; indeed, they are often
attracted to porch lights and lighted windows. The females have short
wings and are usually found around houses only in wooded situations.
The adults are about 3/4 to 1 inch (20 - 25 mm) long and are colored a
drab brown. They require one year to mature.
Other roach species, such as the Australian roach, Smokey-brown roach,
Brown roach and Asian roach, may also be found in Michigan from time to
Roaches lay their eggs in large numbers within a single capsule
(ootheca) which contains from 12 to 32 eggs, depending on the species.
The egg compartments within the capsule are indicated by grooves on the
outside. The egg capsules range in color from dark brown to tannish
brown and are somewhat bean-shaped They are usually deposited in
out-of-the-way places such as on the underside of shelves, inside
cupboard corners, bottoms of drawers, and similar hard-to-see areas.
Egg capsules from which the eggs have hatched will float, while those
that have unhatched eggs will usually sink in water. The nymphs grow
slowly, requiring 2 to 18 months to complete their development.
Integrated Cockroach Management
It is easier (and less costly) to prevent cockroaches from entering a
structure than it is to get rid of them. They can be discouraged from
invading buildings by sealing cracks and crevices in foundations and
outside walls. Check the seal around vents, air conditioners, windows,
doors, utility entrances, and other openings into the home.
Carefully inspect all incoming beverage cartons, groceries, cardboard
boxes, laundry, luggage, used/rented furniture and appliances and
firewood for the presence of roaches or their egg cases.
Indoors, all potential hiding and breeding areas should be eliminated.
Cracks, crevices and holes in floors, walls and ceilings should be
repaired and openings around plumbing fixtures, furnace flues,
electrical outlets, heating ducts, between window sills and walls, and
along baseboards and ceiling moldings should be sealed.
Cleanliness in the home greatly lessens the possibility of cockroach
infestation. Unwashed dishes and kitchen utensils and exposed food
should not be left out overnight. All spilled liquids should be cleaned
up. Cupboards, pantry shelves, storage bins, appliance motor housings
and floors where food particles accumulate should be cleaned often,
first by vacuuming and then with soapy water. Kitchen wastes and dry
pet food should be kept in containers with tightly fitting lids. All
leaky pipes, backed up drains, condensation problems and other sources
of moisture must be repaired or eliminated.
Only after these preventative methods have been employed should you
begin your efforts to control the pests with insecticides or traps. The
first sign of infestation may be scattered roach body fragments on the
floor or individual roaches caught in spider webs. Enter dark rooms
with a flashlight to locate infested areas. Because various
combinations of cockroaches can occur in the same building, it is
essential to accurately identify the species present. This will permit
the use of control measures that take advantage of behavioral patterns
and life requirements of each particular species.
Non Baited Traps can be an effective way to reduce cockroach
populations (especially against brown-banded and German cockroaches),
and whenever possible should be used in combination with preventative
measures and insecticidal treatments. Most cockroach traps are
rectangular or triangular cardboard "boxes" open at both ends with the
inside surface banded with a very sticky adhesive and food attractant.
Roaches enter the trap and are immobilized in the adhesive. Traps
should be positioned (with both ends unobstructed) so as to intercept
roaches as they travel from their hiding places to food sources. If no
cockroaches are caught in a trap after two nights, change its location.
A properly placed trap can catch numerous adults and/or nymphs on a
daily basis (as long as they are replaced when full). Traps are also
important for monitoring cockroach activity; for example, assisting in
species identification, identifying infested areas, determining
relative population density, determining population composition (adults
vs nymphs) and monitoring effectiveness of chemical controls. Traps are
inexpensive, easy to use, disposable and contain no toxic substances.
A variety of ultrasonic pest control devices have been introduced on
the market in recent years. Research on the effectiveness of these
devices has shown a number of these products to have no effect on
cockroaches. The Environmental Protection Agency has taken action to
remove these devices from the market.
Recently, a species of tiny parasitic wasp, Comperia merceti (Compere)
has been used to provide control of brown-banded cockroaches. Other
species of parasitic wasps are known to parasitize cockroaches, and
some of these species may be the biocontrol agents of the future.
Baits or Baited Traps, or Insecticidal baits are available in
ready-to-use containers. They may be used to supplement a control
program. They are a very worthwhile monitoring device. Use the baited
traps before and after initiating a control program to monitor
populations. Baits containing hydoprene, hydramethylnon and propoxur
Residual insecticides leave deposits on treated surfaces which kill
cockroaches for variable periods of time after the application. The
type of insecticide chosen and the application method used will depend
upon the location and nature of the infestation. No one insecticide is
best, but various combinations can be effective. Regardless of the
insecticide chosen, a chemical applied to the areas where cockroaches
rest, hide, feed or walk will kill more individuals than a chemical
applied to areas which cockroaches seldom frequent. Apply residuals to
surfaces less likely to be cleaned. One treatment rarely results in
complete control; retreatments are usually necessary. Frequency of
treatment will depend upon preventative practices, thoroughness of
insecticide application and how vulnerable the structure is to
reinfestation. You will notice roaches around the home even after
spraying because it takes a while for the spray to kill them. They
should begin to disappear in a few days. If you still see roaches a
week after initial treatment, a thorough retreatment is probably in
order. Research has shown that many residual insecticides cause
repellency. When using a repellent product, it is critical to do a
complete treatment if control is to be obtained. If any areas are left
untreated, cockroaches will be repelled from treated hiding places into
untreated ones. Also, avoidance of an insecticide treated surfaces can
be learned by cockroaches exposed to sublethal doses.
Residual insecticides registered for cockroach control are chlorpyrifos
and propoxur. Important limitations of these materials include=
(1) Do not treat entire walls or floors, only small areas of
baseboards, cabinets and other places where
(2) Do not contaminate water, food, dishes or utensils with them; and
(3) Dry all treated surfaces before allowing children or pets on or
In addition to applying a residual spray to surfaces, a pyrethrin or
resmethrin spray can be used. A "total release" aerosol spray is used
to flush roaches out of hiding places after the residual spray has been
applied. This helps assure that the cockroaches will contact the active
residual insecticide. The use of non-residual insecticides alone,
however, seldom gives effective control.
A dust formulation is also suggested to control cockroaches Boric Acid.
Boric acid applied to cockroach runways is ingested by roaches as they
clean themselves, eventually acting as a stomach poison.
If a severe, widespread or persistent cockroach infestation occurs, or
if you are in doubt as to proper control measures, employ a reputable
pest control operator. These professionals have the knowledge, training
and equipment to do a thorough job.
For a complete listing of suggested control options for all home, yard
and garden insect pests contact your local Extension Service, found
under local government in the phone book.
Read and follow instructions on the pesticide label. Heed all warnings.
Check with your physician if you have any concerns regarding your
personal health risk. Revised by Tom Ellis, M.S., Department of
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status. Issued in furtherance of MSU Extension work, acts of May 8 and
June 30, 1914, in cooperation with the U.S. Department of Agriculture.
Thomas G. Coon, Director, MSU Extension, East Lansing,MI 48824. This
information is for educational purposes only. Reference to commercial
products or trade names does not imply endorsement by MSU Extension or
bias against those not mentioned.
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