CHARACTERISTICS: The general form of cockroaches varies little, however their size can range from only a couple of millimetres in length up to 70 millimetres. There are just over 400 species of cockroaches in Australia out of 4000 worldwide, the best known being the introduced pests which commonly inhabit houses, restaurants and sewers. All cockroaches have the following characteristics.
LIFE CYCLE: Cockroaches have incomplete metamorphosis. Most species of cockroaches lay eggs in an ootheca (egg case) that is either deposited on or under suitable substrate, or carried attached to the genital region. The egg stage lasts from a few weeks to a few months. The young are active from hatching and resemble the adults but are usually lighter in colour and lack wings. The young cockroaches develop through a number of nymphal instars, which may range from 2 to 12 depending on the species and may take from a month or so up to 12 months to reach maturity. Some species may live for several years.