The entire life cycle is quite variable, as evidenced by the variability in each life stage progression. As mentioned below, the cycle can be as short as two weeks or as long as two years. That is why it is so important to remain vigilant, even when a flea problem is thought to be under control.

The life and life cycle of the flea
There are many hundreds of species of fleas. Collectively, all of the species of fleas are categorized under the order name of Siphonaptera. The cat flea, Ctenocephalides felix, is the most commonly found flea in the US and infests cats, dogs, humans, and other mammalian and avian hosts.

Fleas thrive in warm, moist environments and climates. The main flea food is blood from the host animal. Host animals are many species – cats, dogs, humans, etc. Fleas primarily utilize mammalian hosts (about 95%). Fleas can also infest avian species (about 5%). Flea saliva, like other biting skin parasites, contains an ingredient that softens, or “digests” the host’s skin for easier penetration and feeding. The saliva of fleas is irritating and allergenic.

Fleas have four main stages in their life cycle: egg, larva, pupa, and adult. The total flea life cycle can range from a couple weeks to several months, depending on environmental conditions.

  • Adult fleas prefer to live on the host animal, but are often dislodged by scratching. The adult flea is very flat side to side. There are hair-like bristles on the flea body and legs to aid in their navigation through pet hair. Fleas have 3 pairs of legs, the hindmost pair designed for jumping. Fleas are well known for their jumping abilities.
    Adult fleas prefer to live on the animal and their diet consists of blood meals courtesy of the host animal. The female flea lays white, roundish eggs. The adult female flea can lay up to 50 eggs per day, 500-600 eggs over several months.
  • Eggs are laid on the animal, but are quite smooth and easily fall off into the environment. The eggs are not sticky (like some parasites), and they usually fall off of the animal into the carpet, bedding, floorboards, and soil. When the flea egg hatches varies – anywhere from two days to a few weeks, depending on environmental conditions. The larva emerges from the egg using a chitin tooth, a hard spine on the top of the head that disappears as the flea matures.
  • Larva (plural = larvae) The larval stage actually has three developmental stages within this stage. Larvae are about 1/4″ (6.35 mm) long, and semi-transparent white. They have small hairs along their body and actively move. They eat the feces of adult fleas (which is mostly dried blood) and other organic debris found in the carpet, bedding, and soil. Depending on the amount of food present and the environmental conditions, the larval stage lasts about 5 to 18 days (longer in some cases) then the larva spins a silken cocoon and pupates.
  • Pupa (plural = pupae) The third stage of the flea larva makes a cocoon where the adult flea develops. The egg, larval, and pupal stages almost always take place in the environment off of the animal, where the microenvironment is often ideal for growth. These larvae and cocoons are found deep in carpeted areas or areas with a layer of organic material (e.g., a garden or flower bed). They are protected from insecticides in this hard-to-reach area. The pupa is the last stage before adult. The adult flea can emerge from the cocoon as early as 3 to 5 days, or it can stay in the cocoon for a year or more, waiting for the right time to emerge. When is the right time? (Never, say pet lovers everywhere!) Stimuli such as warm ambient temperatures, high humidity, even the vibrations and carbon dioxide emitted from a passing animal will cause the flea to emerge from the cocoon faster. This brings us back to the adult flea.

Adult fleas hatch from the cocoon when proper stimulation is present. The stimuli include: vibration, increased carbon dioxide levels, heat, and motion. The adult can emerge from the cocoon in a very short time period…less than a second….and immediately jump to find a proper host. Once on the host they feed on blood obtained by biting through the skin.

An egg may develop into an adult flea within 14 days if conditions are ideal. Each fertilized female may lay as many as 25 eggs per day….more than 800 in her lifetime. In just thirty days, 25 adult female fleas can multiply to as many as a quarter of a million fleas!

The main flea affecting the dog and cat is the cat flea, Ctenocephalides felis. There is a dog flea also that occasionally is responsible for flea infestations, but the majority of the time, C. felis is the flea found on dogs and cats. Fleas are insects that are highly developed and can reproduce in copious amounts when environmental conditions are ideal. High humidity and high relative temperatures provide that ideal environment.

To keep your family and pets safe from fleas, here’s what you need to know…


Fleas can reproduce rapidly at room temperature, making your home an ideal year-round environment.

Their need for blood

Fleas require blood to survive and reproduce. In the absence of a pet, humans become the flea’s blood meal.

The threat of disease

Fleas are capable of transmitting disease to both people and pets – fleas can carry typhus, tapeworms and other diseases.


Fleas go deep within the confines of carpeting, rugs, upholstery and in pet bedding, making their elimination extremely difficult.

Natural protection

Fleas are naturally protected from pesticides during various states of their life cycle. Most pesticides only kill fleas in their larval and adult stages, leaving the un-hatched eggs and pupae to survive, develop and reproduce.

Flea eggs

They can lay dormant for up to 90 days before hatching.


Humans experience small, red itching wounds from flea bites typically around the feet and ankles. Allergic reactions and more serious diseases can occur.

Dark specks on your pet

Pets experience uncontrollable itching and hair loss. “Salt and pepper” found where the pet has been sleeping is a mixture of flea eggs (white) and dried blood (black).

Flea infestations
If you think your environment is infested with fleas, the first step to take is to verify that the pest is actually a flea. This can be accomplished in several ways:

  • Catch the insect with a piece of transparent tape and place in a vial of alcohol and send to a specialist for identification
  • Place white socks over your shoes and pants and inspect to see if any fleas land on the socks as you walk around the area
  • Place sticky insect traps throughout the area, especially near the nests of animals
  • Have your pet examined by a veterinarian for the presence of fleas
  • Use specially designed flea traps to monitor the area

When your dog has fleas
The following are tips to help you alter conditions that are inviting to fleas:

  • Take your pet to a veterinarian for treatment on the same day as your scheduled pest control visit. This dual-treatment is essential to effective flea control
  • Wash all pet bedding thoroughly in hot water or destroy if necessary
  • Vacuum all floors and upholstered furniture thoroughly, especially where pets sleep, to remove both organic debris and as many flea eggs, larvae, pupae and adults as possible
  • Seal used vacuum bag in a plastic bag and remove from house
  • Groom pets regularly outdoors to keep fleas, eggs and larvae from falling off inside the house
  • Trim lawns and weeds to create a drier, uninviting environment for flea larvae
  • When pets go outdoors, minimize their contact with infested animals by keeping them on a leash and in a fenced-in garden

Flea bites
Fleas are one of the more difficult pests to eradicate from homes and work and there is often confusion regarding “paper fleas,” a name given to account for mystery bites when no insect can be found.

Flea saliva injected into a wound during feeding can cause an allergic reaction in some people. Others may find themselves relatively unaffected. Depending on the sensitivity of the person’s skin, the reaction can range from an individual itching weal to a rash localized around the feeding site.

Flea bites generally occur along the ankles and lower portions of the legs. The bite can usually be described as a red spot accompanied by a halo of redness that can last for several hours. Placing an ice cube, camphor, menthol, calamine, or caladryl lotion on the irritated area may provide relief.

Flea bites are similar to the bites of mites and other small parasitic pests. Therefore, for effective pest control, the correct identification of the biting organism is essential.

Diseases transmitted by fleas
In addition to delivering annoying, itchy bites, fleas are capable of transmitting infectious diseases either by direct transmission or by acting as a vector for disease producing organisms.

Flea bite dermatitis: Fleas inject a small amount of salivary gland secretion into the skin when they bite to thin the blood. This saliva may cause a rash like reaction in most victims.

Murine typhus: Fleas can transmit murine typhus to humans from rats, and less often mice. The incubation period for this disease is 6 to 14 days. Murine typhus is rare in the United States, most cases are from Texas.

Plague: Rodent fleas are principle vectors in the transmission of bubonic plague between rats or from rats to humans. The incubation period in humans is from 2 to 10 days. A common scenario is that fleas leave an infested rodent just after its death and switch to humans.

Tapeworm: Fleas are common vectors of tapeworms that infest cats, dogs, and humans. The flea infests the tapeworm eggs when it feeds on infested fecal matter. The eggs develop into cysticeroids inside the flea. The flea is then ingested by a human, cat, or dog. The cysticeroid is then liberated and develops into an adult tapeworms in the digestive tract of the new host.

Flea Myths

  • Fleas can reproduce rapidly at room temperature, making your home an ideal year-round environment.
  • Fleas can only survive in warm climates or during warm summer months.
  • The cat flea is the most common household flea – even on dogs.
  • The most common household flea is the dog flea.
  • Adult fleas can survive without food for a long time.
  • Fleas die quickly unless they’re attached to a food source.
  • Unlike lice, fleas are highly mobile and often not particular about what species they visit. In the absence of a pet, for example, humans become the flea’s blood meal.
  • Fleas only feed on dogs and cats.
  • Fleas are blood-sucking parasites.
  • Ticks, not fleas, feed on blood.

Flea Trivia

  • Fleas can transmit a number of diseases, including epidemic typhus and bubonic plague
  • Fleas also carry tapeworms from dogs and rodents and occasionally transmit them to humans
  • Fleas are generally less than three-sixteenth of an inch long
  • More than 2,400 flea species exist worldwide
  • The lifespan of fleas on dogs is usually more than 100 days, in which time a pair of fleas and their descendants can produce millions of offspring
  • A female flea consumes 15 times its body weight in blood daily
  • Fleas are attracted to animals by body heat, movement, and the carbon dioxide they exhale
  • Fleas accelerate the equivalent of 50 times faster than a space shuttle does after lift off
  • Fleas can jump up to 150 times the length of their bodies – sideways or up – equivalent to a person jumping nearly a thousand feet