COCKROACH

Female cockroach (Periplaneta) also called Roach, any insect of the suborder Blattaria (order Dictyoptera) of more than 3,500 species. The word cockroach is a corruption of the Spanish cucaracha. Cockroaches are among the most primitive living, winged insects (almost unchanged for more than 320 million years) and are among the oldest fossil insects. The cockroach is characterized by a flattened, oval body; long, threadlike antennae; and a shining, black or brown, leathery integument. The head is bent downward, and the mouthparts point backward instead of forward or downward as is the case in most other insects. The male usually has two pairs of wings; the female, often wingless or with vestigial wings, carries eggs in egg cases (called ootheca) that protrude from her body. After the female deposits an egg case, soft white nymphs emerge, hardening and turning brown in colour upon exposure to air. The structure and large size (certain species have a wingspread of more than 12 cm [4.7 inches]) of cockroaches have made them objects of interest in the biological laboratory. The cockroach prefers a warm, humid, dark environment and is usually found in tropical or other mild climates. Only a few species have become pests. The insect damages more material than it consumes and emits a disagreeable odour. The diet of the roach, which includes both plant and animal products, ranges from food, paper, clothing, and books to dead insects, especially bedbugs. Insecticides are used in roach control. The American cockroach (species Periplaneta americana) is 30 to 50 mm long (up to about 2 inches), reddish brown, and lives outdoors or in dark, heated indoor areas (e.g., basements and furnace rooms). During adult life, a period of about 1.5 years, the female deposits 50 or more oothecae, each containing about 16 eggs that hatch after 45 days. Nymphal life lasts from 11 to 14 months. The American cockroach, a native of tropical and subtropical America, has well-developed wings and can fly long distances. The German cockroach (Blattella germanica), a common household pest sometimes erroneously called a waterbug, is light-brown with two dark stripes on the prothoracic region. The female produces the ootheca three days after mating and carries it for about 20 days. Because it is small (about 12 mm [less than 0.5 inch] long), this cockroach often is carried into homes in grocery bags and boxes; it has spread throughout the world by ship. Three or more generations may occur yearly. This cockroach, abundant around the water pipes of the Croton Aqueduct in New York City, became known as the Croton bug. The brown-banded cockroach (Supella supellectilium) resembles the German cockroach but is slightly smaller. The male has fully developed wings and is lighter in colour than the female, whose wings are short and nonfunctional. Both sexes have two light-coloured bands across the back. The adult life span is about 200 days, and there may be two generations annually. Eggs may be deposited in clothes, wood molding, or cracks in the floor. With the advent of heated buildings this cockroach became established in cooler climates. The Oriental cockroach (Blatta orientalis) is considered one of the filthiest of household pests. It is oval, shiny black or dark brown, 25 to 30 mm long, with a life cycle similar to that of the American cockroach. The male has short, fully developed wings, and the female has vestigial wings. This cockroach has been distributed by vehicles of commerce from its Asiatic origins to all the temperate regions. Wood roaches are not domestic pests. Parcoblatta pennsylvanica, the common wood cockroach, is found under logs and stones in northern latitudes. The male and female are so different in appearance that they were once considered separate species. The male, 15 to 25 mm long, has wings that extend past the abdomen; the female is smaller and has much shorter wings. Cryptocercus punctulatus digests wood with the aid of certain protozoans in its digestive tract.