After mating, eggs develop in the female in a purse-shaped egg case called the ootheca, which can contain between 12 and 40 eggs, depending on the species. The ootheca may be glued to a surface and left unattended or dropped just prior to hatching.
Immature cockroaches, referred to as nymphs, emerge from the egg cases. Nymphs look like small versions of the adults but do not have wings. The nymphs grow into adults through a number of moults which takes between two months and a year, and then live as adults from a few months to over a year, depending on the species. During her adult life, a female may produce between 5 and 30 oothecae.
Cockroaches are omnivorous, which means they eat virtually any organic matter.
The pest species of cockroach are gregarious, forming groups of adults and immature nymphs. They are mostly nocturnal creatures, hiding during the day. Cockroach activity during the day indicates a cockroach overpopulation. Most pest species need ready access to water.