Cockroaches are among the most common of insects. Fossil evidence indicates that cockroaches have been on earth for over 300 million years. They are considered one of the most successful groups of animals. Because cockroaches are so adaptable, they have successfully adjusted to living with humans. About 3,500 species of cockroaches exist worldwide, with 55 species found in the United States. In the northeastern United States, only four species are common pests in structures. These are the German, brown-banded, Oriental, and American cockroaches.
Cockroaches are “living fossils”. This means that their basic shape and appearance has not changed for millions of years. Fossil remains of cockroaches have been dated before the appearance of the Dinosaurs and appear virtually identical to cockroaches we find today.
This is the most common cockroach found in homes and food service establishments and has the highest reproduction rate of the four common cockroaches. After mating, the female cockroaches produce an “egg capsule” containing 30-40 eggs. 1-2 days before the eggs hatch, the female drops the capsule in a sheltered area. The development time from egg to adult takes about 100 days. The female will produce about 3-4 egg capsules in her lifetime which is about 100-200 days. Because of the high rate of reproduction, in very short order, the home or apartment can be totally infested with thousands of cockroaches.
Cockroaches will eat virtually any item that has nutritional value. This includes dog food, any human food items and even soap and glues.
The German cockroach has been identified as a trigger of asthma in sensitive individuals especially children. Exposure to cockroach fecal material, saliva and body fragments can trigger an asthma attack. Cockroaches have been shown to carry bacteria on their bodies and are potential sources of salmonella food poisoning.
American cockroaches are often called water bugs. The American cockroach is the largest of the species common to the northeast. This species often becomes abundant in city dumps and is most common in the basements and steam tunnels of restaurants, bakeries, food-processing facilities, and grocery stores.
Adults are approximately 1-1/2 inches long and reddish brown, with fully developed wings that cover the entire length of the abdomen (Fig. 1). Both male and female are fully winged. American cockroaches are capable of flying but rarely do in northern areas of the United States. The American cockroach can be identified by its large size and reddish brown color with faded yellow edges on the thorax.
When indoors, the nymphs and adults are usually found in dark, warm and moist areas of basements and crawl spaces, and in and around bathtubs, clothes hampers, floor drains, pipe chases, and sewers. They are also common around the manholes of sewers, and on the undersides of metal covers over large sump pumps. In the north, this cockroach is often associated with steam heat tunnels. It has also been observed migrating from one building to another during warm months in the north.
American cockroaches feed on a variety of foods, with an apparent preference for decaying organic matter. The adults can survive two or three months without food but only about a month without water.
American cockroaches have three developmental stages: egg, nymph, and adult. The eggs are laid in capsules that are dark brown, symmetrically shaped, and about 5/16 inch long. The female drops her egg capsule within a day after it is formed. She often drops it in a suitable location near a food source or in a protected area. Each capsule averages 14 to 16 eggs. Usually one capsule is produced each week and is often glued to a hidden surface with secretions from the female’s mouth. Each female produces from 15 to 90 egg capsules.
Oriental cockroaches are often called water bugs because of their preference for dark, damp, and cool areas such as those under sinks and washing machines, and in damp basements. This species, which is less wary and more sluggish than the others, is of concern because it often travels through sewer pipes and lives on filth.
Adult Oriental cockroaches are about one inch in length. Both male and female adults are very dark brown, nearly black; their bodies usually have a somewhat greasy sheen. Females have small, functionless, rudimentary wing pads and broader, heavier bodies. Males have wings that cover only about three-quarters of their abdomen. Males are apparently unable to fly.
Nymphs and adults have similar habits and are found with decaying organic matter indoors and out. Indoors, Oriental cockroaches prefer dark, moist areas such as under porches, sewers, drains, crawl spaces, dark, damp basements, and floor drains. They can be found outdoors in abandoned cisterns and water valve pits; in yards; beneath leaves; in bark mulch around shrubs, flowers, and foundations; in dumps, stone walls, and crawl spaces; and in garbage and trash dumps and trash chutes. Both nymphs and adults are sluggish and are usually situated at or below ground level indoors. They are seldom found on walls, in high cupboards, or in the upper floors of buildings. At times large numbers occur in one great mass around leaks in the basement or crawl space areas of homes. Oriental cockroaches are generally found outdoors during warm weather, but in periods of drought there may be considerable movement into structures, apparently in search of higher humidity. They may enter the home in food packages and laundry, or merely come in under the door or through air ducts, garbage chutes, or ventilators.
The Oriental cockroach has three developmental stages: egg, nymph, and adult. Eggs are laid in capsules, which the female carries for about 30 hours and then drops onto a protected surface near a food supply. The female does not glue the egg capsule to the surface. Females produce an average of eight capsules, each containing 16 eggs that hatch in about 60 days under room temperature conditions. The life span of an adult female is 5 to 26 weeks with approximately 200 offspring. Unlike the other house-infesting species, the Oriental cockroach generally has a seasonal developmental cycle. The peak number of adults usually appears in late spring or early summer. By late summer and early fall, this number has become quite low, owing to natural mortality and the hatching of nymphs.
Adult male brown-banded cockroaches are about 1/2 inch long and light brown, with fully developed wings. Both adults and nymphs can be distinguished by the two brownish, broad-bands across the body at the base of the abdomen and at mid-abdomen. Both males and females are quite active; adult males fly readily when disturbed.
Brown-banded cockroaches prefer warm and dry locations, such as near refrigerator motor housings, on the upper walls of cabinets, and inside pantries, closets, dressers, and furniture in general. They can also be found behind picture frames and beneath tables and chairs, and inside clocks, radios, light switch plates, doorframes, and dressers. It is common to find them hiding nearer the ceiling than the floor and away from water sources. Accurate identification is paramount to controlling brown-banded cockroaches. Control strategies for other cockroaches will not be efficacious for brown-banded cockroaches.
The brown-banded cockroach has three developmental stages: egg, nymph, and adult. Eggs are laid in capsules, which the female carries for about 30 hours before she fastens it on walls, ceilings, and in protected and hidden areas. During her adult life a female produces about 14 egg capsules, each containing an average of 13 eggs. The length of the egg stage varies from 37 to 103 days, depending on temperature. The nymphal stage ranges from 8 to 31 weeks. A female adult has a life span of 13 to 45 weeks; each female produces about 600 descendants per year.