Adult fleas are approximately 2.5 millimeters long, and flea larvae are 1.5 millimeters long. Fleas stay in the larval stage for 18 days before creating a cocoon, where they stay for two weeks until they reach the adult stage.
Fleas have six legs and no wings, their compact bodies are covered in tiny hairs, and they can jump 13 inches horizontally or 7 inches high. These insects are easily noticeable despite their small size because they quickly populate the body of their host, which generally includes cats, dogs and other mammals. Typically, fleas do not prefer to feed on humans.