The Flea Life Cycle
To properly control fleas, it is best to understand the flea life cycle.
The Egg Stage
Adult fleas can begin feeding within seconds of finding a host. They must feed to begin reproduction, and female fleas will begin producing eggs within 24 to 48 hours of taking their first blood meal.
Female fleas can produce 40 to 50 eggs per day, up to 2,000 in their lifetime.1 The eggs readily fall off the hair into the environment, so you can think of your pet as a flea-egg “salt shaker.” Wherever the pet spends the most time is usually where the heaviest flea infestations are found.
The Larva Stage
Larvae hatch from eggs in one to six days given appropriate environmental conditions (a relative humidity between 50 and 92 percent). Their principal food is adult flea feces (“flea dirt”).
Flea larvae are small, thin and white, measuring 1 to 2 millimeters in length (about the thickness of a dime). Indoors, flea larvae tend to live deep in carpeting or under furniture. Outside, they develop best in shaded areas or under leaves or similar yard debris. Any area of a yard where a pet seeks shelter from the heat or cold is potentially a great environment for fleas.
The Pupa Stage
A mature larva transforms into a pupa inside a silk cocoon. Under most household conditions, the adult flea will emerge in three to five weeks. However, a fully developed flea can remain inside the cocoon for up to 350 days,4 a reproductive strategy that enhances the flea's chance of survival. This helps to explain how a flea infestation can seemingly “explode” out of nowhere, even inside your home.
The Adult Stage
Adults emerging from cocoons can begin feeding immediately if a host is present. They are attracted by body heat, movement and exhaled carbon dioxide.
The flea feeds through a tiny, slender mouth part called the proboscis. Before feeding, it pumps saliva, which contains an anticoagulant, onto the skin. This prevents the blood from clotting, and the protein it contains can cause a severe allergic reaction in the host (flea allergy dermatitis).