American cockroach adults grow to an average length of around 4 centimetres (1.6 in) and about 7 millimetres (0.28 in) tall. They are reddish brown and have a yellowish margin on the body region behind the head. Immature cockroaches resemble adults except that they are wingless.
The insect can travel quickly, often darting out of sight when someone enters a room, and can fit into small cracks and under doors despite its fairly large size. It is considered one of the fastest running insects.
In an experiment carried out at the University of California, Berkeley in 1991, a Periplaneta americana registered a record speed of 5.4 kilometres per hour (3.4 mph), about 50 body lengths per second, which would be comparable to a human running at 330 kilometres per hour (210 mph).
It has a pair of large compound eyes each having over 2000 individual lenses, and is a very active night insect that shuns light.
Risk to humans
While cockroaches do not typically bite and are not poisonous, they can pick up disease-causing organisms which after growing and multiplying in their guts can subsequently be deposited on kitchen surface areas, utensils, and food items. In addition, “cockroaches can pick up disease-causing bacteria like Salmonella on their legs and later deposit them on foods and cause food poisoning”. House dust containing cockroach feces and body parts can trigger allergic reactions and asthma in certain individuals.