The Oriental cockroach is often called the water bug, and sometimes the black beetle, or just plain, beetle.
Adult Oriental cockroaches are very dark-brown or shiny-black. The female is slightly longer than the male – 1 1/ 4 inch, with a broad abdomen and stubby wings. The male is 1 inch long, slender and has wings which cover 2/3 of the abdomen. Unlike other domestic cockroaches, the female does not develop wings, but produces only short triangular wing pads. Neither sexes will fly nor even run quickly when disturbed. The male has wings, but they are short and broad, leaving about 1/4 of the abdomen exposed.
Eggs. The Oriental cockroach female produces an average of eight egg capsules from spring to midsummer. Unlike other urban cockroaches, the Oriental roach produces only one generation per year where temperatures are cool in winter. The egg capsule is carried for little more than 24 hours, and then is placed in a protected spot; it is irregularly shaped, black, 3/8 inch long, and 1/4 inch wide. Anywhere from 8-15 egg cases are produced per female with each egg capsule containing 16 eggs and hatch in two months.
Nymphs. Nymphs are the same color as the adults. The nymphal stage requires about one year for completion. Nymphs are active from about March through much of the summer. During this period they molt seven to ten times, and are reddish-brown to black in color, except in the first stage when they are pale tan. The older brown Oriental cockroach nymphs are very difficult to distinguish from the American cockroach nymphs.
Adults. In early spring, only adult Oriental cockroaches are found. By late spring, nymphs are abundant. As nymphal numbers increase, the adults die off and by August any adults are new ones. By fall, almost the entire population is adult. Neither males nor females fly.
Behavior and Harborage
Oriental cockroaches favor crawl spaces, spaces between the soil and building foundations, the undersides of stoops and sidewalks, landscaping mulches, water meters, basements and their floor drains, and other such moist places. These cockroaches are more sensitive to lack of water than other roaches. These cockroaches frequently live in floor drains that drain directly outside; these drains are also used as entrances to homes. Oriental cockroaches invade structures through sewer drain pipes, foundation cracks, ventilators and poorly fitting doors.
Outdoors. These insects dwell in cool, moist habitatsbeneath decomposing leaves or stones in flower and garden mulching materials, in trash and garbage piles, and in municipal sewer systems. The Oriental cockroach prefers starchy food, and builds up populations around garbage cans. They tolerate lower temperature ranges than other roaches and may winter in rock walls or such protected sites.