The Life Cycle of a Flea

The flea life cycle – in more detail than you ever thought possible!

Life Cycle of a Flea


Stages in the Flea Life Cycle

The life cycle of a flea has four stages: egg, larva, pupa, and adult. By the time you see an adult flea on your pet, they almost certainly have lurked silently for a month or more as their eggs hatched into larvae and their pupae cocooned.

The fleas’ life cycle takes anywhere from two weeks to several months to complete, this depending on the environmental conditions. Optimal conditions for fleas are between 70 and 85 degrees Fahrenheit and 70 percent humidity. Humidity lower than 50 percent and temperatures higher than 95 degrees Fahrenheit will kill flea larvae. The more favorable the conditions are for fleas, the faster (and more frequently!) the flea life cycle is completed.


Flea Eggs

Flea Eggs

In the first stage of the flea lifespan, female fleas lay eggs while attached to a host. A flea can lay anywhere from four to 20 eggs at a time, but always after a meal. The highest concentration of egg-laying occurs at the end of a female’s life, but she can lay 500 eggs throughout her life span.

What do flea eggs look like? Flea eggs are white and slightly smaller than a grain of sand. The eggs are smooth and fall off the host easily, especially when they move. This is how the eggs become dispersed through the environment.

Flea eggs will hatch anywhere from two to 14 days after being laid. The eggs will “wait” for favorable conditions and hatch faster in warm temperatures and high humidity. Eggs represent about half of the entire flea population in an average home.


Flea Larvae

Flea Larvae

The second stage in the life cycle of a flea is the larval stage. When the flea eggs hatch, the flea larvae emerge.

What do flea larvae look like? Flea larvae are small and maggot-like, with no eyes or legs. As they complete three larval stages, or instars, they will range from 3 to 5 millimeters in length and turn progressively darker.

Larvae, the first stage of the flea lifespan, make up about 35 percent of the average household’s flea population.

Flea larvae are blind, but they are programmed to avoid light and seek dark, warm places. They love to burrow into the carpet, furniture, and bedding. They can also be found under skirting boards or in crevices.

Flea larvae eat pre-digested blood (known as flea “dirt”) that makes up adult fleas’ droppings. They also consume other organic debris, such as hair, dead skin cells, food particles, feathers, dead insects, and cells shed from their own skin.

The flea’s larval stage usually lasts four to 20 days under favorable conditions, but the process can take up to 200 days in a less favorable environment. The last thing a flea larva does is spin a silken flea cocoon that protects it during the pupal stage.


Flea Pupae

Flea Pupae

The flea life cycle’s pupal stage typically lasts five to 14 days but can take several weeks. Flea pupae account for about 10 percent of a flea population.

What do flea pupae look like? The pupa and its flea cocoon are about 4-5 millimeters long and 2 millimeters wide.

The flea cocoons protect the flea pupae while they develop into adults, so flea pupae cannot be killed with chemicals. Cocoons have a sticky coating that attracts debris and makes them harder to remove from carpet and crevices.


Adult Fleas Emerge

Adult Fleas Emerge

A fully developed adult flea will not emerge from its cocoon until a host is available. Like many insects that feed on blood, fleas can sense the increased carbon dioxide levels that indicate animals’ presence. They can also sense movement and vibrations. Once an adult flea has emerged, it will hop onto the first host that passes by. From there, flea reproduction is their goal. As the females search for a place to lay eggs, the males search for females, and all are eager for a meal.

That meal is key to flea reproduction. After a flea has emerged from the cocoon, it needs to eat within a few hours. If a female flea emerges from her cocoon and can’t find food, she’ll die without contributing to flea reproduction. An adult flea will begin to feed within 10 seconds of landing on a host.

What do adult fleas look like? Adult fleas are about 1 to 3 millimeters long and are reddish-brown to black in color. New adult fleas have a flat-bodied appearance but will become larger and lighter as they feed, taking on their classic flea shape. Adult fleas have no wings but have long back legs that make them capable jumpers.

Some adult fleas spend time lurking on surfaces. Other adult fleas spend their time primarily on a host, and they can stay indefinitely if not dislodged. If they jump off or are knocked off, such as by the animal’s grooming efforts, they will eventually seek another host (or return to the same host).

An adult flea’s lifespan can last as long as a year if the flea has a suitable host or hosts. The flea’s lifespan without a host is only a couple of weeks; during this time, the flea pupae are still lying in wait. While adult fleas are the most visible, they only make up less than 5 percent of a flea population.

An adult female flea will begin laying eggs shortly after her first meal, within a few days of emerging from her cocoon. And, those are the flea eggs that begin a new life cycle of fleas.

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