Fleas are ectoparasites that consume blood from hosts. Ectoparasites are parasites that live on the outside of a host's body. Fleas feed on warm-blooded hosts including dogs, cats, mice, humans, rabbits, squirrels and chickens.
Fleas do not have wings and are very small, ranging in length between 1.5 and 3 millimeters. Though fleas cannot fly, they are capable of jumping 7 inches vertically and about 13 inches horizontally, making them some of the best jumpers known, considering their body size. New fleas require a host within a couple of days, while adult fleas can go for months without feeding. Some other common ectoparasites include lice and ticks.