Cockroaches are one of the oldest groups of insects, indicating how successful they have been in adapting to changes in their environments. One reason for this success may be related to diet--they are scavengers and will eat anything organic. They prefer food sources such as starches, sweets, grease and meat products, but other items may include cheese, beer, leather, glue, hair, starch in book bindings, flakes of dried skin or decaying organic matter (plant or animal).