Skip to main content

Understanding the Flea Life Cycle

When it comes to eliminating fleas from your pet and from your home, there are some key things to consider. One of the most important things is life cycle of the flea, which depending on the environmental temperature and humidity levels can take between a couple of week to many months. There are four stages in the life cycle of a flea: egg, larva, pupa, and adult. Here we will discuss all four…

Image: Francisco Javier Ballester Calonge / Shutterstock

1. Eggs

It all starts when an adult female flea lays eggs following a blood meal from the host (e.g., your pet). These eggs are small, white objects (slightly smaller than a grain of sand) that are laid in the pet’s fur in bunches of about 20. The eggs will fall off your pet as it moves, allowing them to be disbursed throughout the environment where the pet spends its time. Eggs take anywhere from two days to two weeks to develop, hatching when environmental conditions are just right. Larvae then emerge as the next life stage.

Image: Denni Schnapp / Flickr

2. Larvae

The emerging larvae are blind and will avoid being out in the light. They develop over several weeks by eating pre-digested blood (known as flea “dirt”) that adult fleas pass, along with other organic debris in the environment. Flea larvae, which are white and legless, can be up to ¼-inch long. If conditions are favorable, the larvae will spin cocoons in about 5 to 20 days of hatching from their eggs.

Image: Peter J. Bryant /

3. Pupae

This cocoon stage is the last developmental stage before the adult flea emerges. It has a sticky outer coating that allows it to hide deep in the carpeting and not be easily removed by light vacuuming or sweeping. The cocoon protects the pupae for several days or weeks before the adult flea emerges. If environmental conditions are not right for emergence, the cocoon can protect the developing flea for months, and in some cases, years.

Image: Sean McCann / Flickr

4. Adult Fleas

Once a flea has emerged from the cocoon, it will need to begin feeding from a host within a few hours. Shortly after the first meal, adult fleas will breed and begin laying eggs within a few days. New adult fleas have a flat bodied appearance and are very small and dark in color. Once they feed, however, they will become larger and lighter in color, taking on the more recognizable flea shape. They spend the majority of their time living on the host while they feed, breed, and lay eggs, and can live anywhere from a couple of weeks to several months on the host animal.

Image: Cosmin Manci / Shutterstock

Eliminating Fleas

Use your knowledge of the flea life cycle to eliminate an infestation. Treat the environment properly by vacuuming regularly for several weeks and thoroughly washing bedding and toys in hot soapy water to remove eggs, larvae, and pupae. Treat the adult fleas living on your pet with shampoos, sprays, dips, or spot-on medications. If you have any questions or concerns your veterinarian can help you make the best decision for treating your pet.

Image: David Mzareulyan / Shutterstock

Redirection Path

Help us make PetMD better

Was this article helpful?