The above picture shows the life cycle of a cockroach through the three stages of incomplete metamorphosis:
(1) egg, (2) nymph and (3) adult.
There is no inactive, non-feeding pupal stage.
Cockroaches are attracted to warm, moist environments. They spend the daylight hours in dark, secluded sites under refrigerators, stoves, false bottoms in kitchen cabinets, in the backs of cabinets and in crevices between baseboards and floors or cabinets and walls. They may also be found behind pictures or within electronic equipment. A number of these openings will ultimately lead to voids in the stud walls. The insects leave these sites at night to forage for food and water. The presence of cockroaches during the day may indicate a large population.
There are about 3,000 species of cockroaches in the world of these, three are most common i.e. the German cockroach, the American cockroach and the brownbanded cockroach.
The German cockroach is 12 to 17 mm (1/2 to 5/8 inch) long, tan to light brown, and has two dark brown stripes on the body region (pronotal shield) just behind the head. Females will produce four to eight egg capsules during their lifetime, with each capsule containing approximately 40 eggs. The egg capsule is retained by the female until the eggs are ready to hatch, usually in 28 to 30 days.
German cockroaches are widespread and can be found in homes, restaurants, hospitals, nursing homes or apartments. Within these areas, the cockroaches prefer sites close to moisture and food, making them common pests in kitchens, bathrooms and food-storage areas. Of the cockroaches which infest structures, the German cockroach is probably found more frequently than other species.
The American cockroach is one of the largest cockroaches in the Northeast. It is about 40 mm (1.5 inches) long with a reddish-brown body. The center portion of the pronotal shield is light brown, while the outer edges are yellow. Even though both sexes are winged, their flight is more of a gliding movement from point to point than active flight
The female American cockroach will not retain the egg capsule for more than a day after its formation, instead dropping the capsule in some suitable site. Under some conditions it may be glued to a surface. The number of capsules produced by a female will range from 6 to 14, with each capsule containing 14 to 16 eggs. The eggs hatch in 50 to 55 days.
The American cockroach prefers dark, moist sites where it feeds on decaying organic matter. Such sites include basements, kitchens, clothes hampers, drains, bathroom plumbing or sewers. High populations have been known to develop in sewers, from where they infest households or other structures.
The brownbanded cockroach is 12 mm (1/2 inch) long, light brown, and has two lighter colored bands running across the body. These bands are located at the base of the wings and on the abdomen. The bands are much darker during the immature stages. The brownbanded female carries the egg capsule for 24 to 48 hours before gluing it to a surface. The capsule contains approximately 18 eggs that hatch in 50-74 days. An adult female produces about 18 egg capsules over a life-span of 10 months.
The brownbanded cockroach requires less moisture than other cockroaches. It is more prevalent in homes, apartments, hotels and hospital rooms than in restaurants or stores. Evidence of this cockroach may be found behind pictures, in furniture, the underside of chairs and tables, upper kitchen cabinets or the upper shelves of closets and pantries. The brownbanded cockroach often infests electrical appliances such as radios, televisions, telephones and computers.