Female cockroaches produce egg cases, known as oothecae. Oothecae contain many eggs and are enveloped by a protein substance that gradually hardens into a strong, protective casing. Some cockroach species drop the egg case, while other species carry it until the eggs are ready to hatch.
The American cockroach’s ootheca is dark brown in color and averages 8 mm in length. One female may create six to 90 oothecae in her lifetime. The female American cockroach carries the ootheca for a few hours to a few days, at which point she deposits the egg case in a safe, hidden location. The American cockroach ootheca contains approximately 15 embryos and remains in place through the use of the female’s saliva. Immature cockroaches will emerge from the ootheca within 24 to 38 days.
The brown-banded cockroach’s ootheca is light reddish-brown in color and measures approximately 5 mm in length. Females of this species produce up to 20 cases in one lifetime, and each case hatches 10 to 18 embryos. Brown-banded nymphs are identifiable by two yellow bands that cross their upper abdomens. Nymphs develop fully to adults within three to six months.
The Oriental cockroach creates a dark reddish-brown ootheca that is 8 to 10 mm in length. These oothecae appear slightly inflated and each contains approximately 16 eggs. The female deposits the egg case in a favorable environment after it is produced. Females produce between one and 18 egg cases in a lifetime. Nymphs typically take around 600 days to become adults, although their development is dependent upon environmental conditions.
The German cockroach’s ootheca is brown in color and typically measures less than 6 to 9 mm in length. The female German cockroach carries the ootheca until the eggs inside it are ready to hatch. One ootheca can contain up to 50 eggs. Egg to adult takes 103 days, on average. Because they produce so many eggs that develop so quickly, their population grows very rapidly.