There are twelve species of cockroach, however, the most common in the UK are the german cockroach and the oriental cockroach. The adult
german cockroach (also known as the steamfly) is 10-15mm long, yellowish brown in colour with two longitudinal dark marks. The wings are well
developed. They can climb rough and polished vertical surfaces. The adult oriental cockroach (also known as the black beetle) is 20-30mm long,
dark brown/nearly black in colour. The males have wings which cover two thirds of the abdomen, the females do not have developed wings. They
can climb rough vertical surfaces, but not smooth.
The nymphs (young) of all species are similar in appearance to the adult but smaller. Immediately after hatching the nymphs are white, but the
cuticle soon darkens to the normal colour.
Cockroaches are nocturnal and are most active at night. Any sudden light will cause them to scurry for shelter. The german cockroach prefers
warmer, humid environments, while the oriental cockroach is frequently found in cooler, less humid areas such as basements and drains.