Most species of cockroaches engage in courtship rituals before mating. Sometimes the male will tap the female’s body with his antennae. He then turns around, flaps his wings and extends his abdomen. Doing this exposes two glands that secrete a substance that the female feeds on. The male then moves backwards under the female, inserts his penis in her genitalia, and rotates 180 degrees. The pair remains attached for as long as it takes the male to transfer his sperm to the female.
Over the next few days, the female will lay several dozen eggs in a protective capsule called an ootheca, which is produced in her abdomen. The majority of species will deposit the fully formed ootheca in a damp place. German cockroaches (the most common indoor species) carry the ootheca protruding from the abdomen for three to four weeks.
The larvae hatch soon after the ootheca is deposited. Young cockroaches resemble adults, but are wingless. They undergo four to fifteen moults before reaching maturity.
Several species are oviparous (eggs are produced in the ootheca). Others are ovoviviparous (eggs are retained in the female’s body until ready to hatch).
Indoor species can lay eggs all year long. The life cycle varies according to the species. German cockroaches, for instance, can live more than 200 days. Developmental time (egg to adult) is 60 days at 27°C and 40% relative humidity. This species produces three to four generations per year.