There are many species of fleas, including the cat flea, dog flea, human flea and rat flea. Of these, the cat and dog fleas are the most common and are often found together.

These fleas are small, wingless insects about 1/8-inch long, dark colored, and have very narrow bodies with well-developed legs which allow them to be great jumpers. Their bodies are covered with backward projecting spines that help them move between the hairs on the host animal.

Cat and dog fleas go through complete metamorphosis. The female lays four to eight eggs after each blood meal. The eggs fall into the nest of the host animal or wherever the animal happens to be at that particular time. The eggs hatch in about ten days. The larvae feed on dried blood, bits of feces, and other types of food materials. They go through three molts in from seven days to several months, depending on temperature. When mature, they spin silken cocoons within which they pupate. The pupal stage lasts from seven days up to a year. The adult flea will often stay within the cocoon until vibrations stimulate them to emerge.

To facilitate control of these insects, the structure should be thoroughly vacuumed to remove larvae and pupae, as well as food materials. Pet bedding should be discarded or washed in hot soapy water, and the pet should be professionally treated as often as the veterinarian recommends.