Cockroach, swift-running, flattened, oval-shaped insect belonging to order Dictyoptera. Although in their native regions they live outdoors, several species are important domestic pests. All are general feeders, nocturnal in habit, guided by long antennae while scavenging in kitchens, bathrooms, cellars, restaurants and moist, warm places.


Of the 3500 species known worldwide, most are tropical and subtropical. Only 10 occur in Canada, of which 7 have been introduced through commerce and immigration. Three or 4 species of wood cockroach (Parcoblatta) live in leaf litter and debris outdoors in Ontario and western Québec. The most common cockroaches are the 5 cm long American cockroach (Periplaneta americana), the 2-5 cm Oriental cockroach (Blatta orientalis), the brown-banded cockroach (Supella longipalpa) and the up to 2 cm German cockroach (Blattella germanica). The last is the most common urban species.

Reproduction and Development

After mating, the female produces 20-50 eggs that are retained in a leathery case (ootheca) projecting from the genital chamber. In some species, eggs hatch within this chamber, receive nourishment from the mother, and nymphs emerge alive. Nymphs grow slowly, molt as often as 13 times and mature in 3-12 months. Adults live for several years.

Interaction with Humans

Cockroaches not only contaminate and destroy food but also carry disease-causing bacteria and secrete foul-smelling matter. A few have symbiotic protozoa or bacteria in the gut to help them digest wood and other vegetation.