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Michigan State University Extension
Home Maintenance And Repair - 01500526
06/24/03

Cockroaches



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 "cucaracha."

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 greenhouses.

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 individuals.

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 time.

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.

Control

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-chemical Controls

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.

Ultrasonic Devices.

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.

Biological Control.

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 are suggested.

Residual Insecticides.

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
cockroaches occur;

(2) Do not contaminate water, food, dishes or utensils with them; and

(3) Dry all treated surfaces before allowing children or pets on or near them.

Non-residual insecticides.

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.

Professional Control

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 Entomology

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This information.was reviewed as of June 2008.  For more information about the contents please contact costner@msu.edu for webpage problems strausc@msu.edu .