Most species are quite active and move through the hair rapidly when disturbed. The sticktight flea attaches permanently in less hairy areas, as around the eyes or ears. They have no wings. Most are brown with legs well developed for jumping. A generation may be completed in a month.
Fleas deposit small white eggs on the animal, which usually fall off into the bedding area.
The larvae are white, worm-like, and legless. Larvae feed on organic matter such as hair, and on flea excreta which is partially dried blood. The pupal form usually is enclosed in a silk cocoon, encrusted with sand and organic material. Newly emerged adults soon seek a host and spend most of their life on the host. Fleas suck blood, and heavy populations can cause anemia, particularly in young, old, or sick animals.