Cockroach’s life cycle begins with the egg. Cockroach eggs hatch through the pressure of capsule. After emerging from egg capsules or oothecae, immature cockroaches are called as nymphs. Nymphs are bright white in color initially. They grow up through intake of air and will harden and darken with hours. The recent studies consider that available food sources within the first 12 hours of molting greatly affects the growth of cockroach nymphs.

Cockroach nymphs are grayish – brown in color and it will darken after each molting before being adults. After each molting, nymphs start being similar to adult cockroaches. In some species, this process only take in a few weeks whereas it can last up to a year for Orient Cockroaches. Cockroach nymphs are the same as their adults and they have to pass many molting. The last molting is the time that they develop fully to adults.

German Cockroaches measure less 3 mm when they hatch. After darkening, they are nearly black in color with a light patch located on the back. This patch will become more pronounced through the second and third molting stages. Brown-banded cockroach nymphs have two bands on their bodies which range in color from black to light gold. American cockroach nymphs are gray-brown in color and gradually redden.