The mouthparts look especially painful in this close-up view of the business end of an adult flea. Hoffman modulation contrast was used to increase contrast in this photomicrograph of the unstained specimen.

Fleas thrive in a warm and humid environment and, while wingless, they can jump as high as two feet. Approximately one percent of an entire flea population exists in the adult stage, making it critical to treat the entire environment when dealing with an infestation. Adult fleas are triggered to jump by a passing shadow and they can live for several months without food. Once attached to a host (dog, cat, human, etc.) they become permanent residents, although they only survive for three to four days after a blood meal. A female adult flea can lay only approximately 20 eggs per setting, but she is capable of producing up to 500 eggs in a lifetime.