Cockroach eggs hatch after incubating for a period of time ranging from about two weeks to two months. Newly hatched cockroaches are called nymphs and look like smaller, wingless adults. Nymphs grow by shedding their skin, or molting, multiple times during the early stages of development. The most common species of cockroach found in North America, the German cockroach, molts six or seven times before developing into an adult in about three months. Brown-banded cockroaches mature within a few months, while other cockroach species, such as American and Oriental cockroaches, can take longer than a year to reach adulthood. The presence of molted cockroach skins, even in the absence of the actual insect, is often evidence of an infestation.