Fleas are insects that live as parasites on birds and mammals, including humans. They depend on the animal they live on for food. Fleas bite the animal and feed on its blood. They can spread diseases. There are about 1,600 species of flea. The largest individual is only about 1 centimeter long. Fleas are excellent jumpers.
A flea has four stages of life: egg, larva, pupa, and adult. A female flea can lay more than 20 eggs every day. Adult fleas live for a few weeks to about a year.
Fleas commonly spend a great deal of time off their hosts, for example, in vegetation or on the ground. They can generally survive for a long time without feeding.