Fleas are small, very specialised parasitic insects that belong to the Order Siphonaptera. This insect order is fairly small, having some 2380 species known worldwide and only about 90 species represented in Australia. Adult fleas are blood suckers, the majority feeding on mammals (eg; dogs, cats, pigs) and some feeding on birds.

Some flea species are very widespread and as a result of their biting habit, which may cause severe irritation, and their role in disease transmission, the group has justly earned a reputation of being extremely important in the medical and public health context. When conditions favour flea growth and development, populations can be so great that refrences to a 'flea plague' are not uncommon. The interactions between flea populations and humans and their animals can be quite complex. In some instances, control may be difficult to achieve without the assistance and cooperation of the occupants of the building concerned. A sound understanding of the biology of fleas is an important prerequisite to effective control.