Cat Fleas

Facts, Identification, & Control

Scientific Name

Ctenocephalides felis


What Do Cat Fleas Look Like?

Cat Flea Photo

Cat fleas are small, dark brown to black insects whose bodies are hardened and look compressed when viewed from side to side. They do not fly, but have strong hind legs that they use to jump and their mouthparts are designed to pierce the skin of their host and suck blood. While not seen unless using a microscope or dissecting scope, adults have spines on and near the head. These are important characteristics that professionals use to identify various flea species. Adult cat fleas are about ¼ inch long and wingless. The adult is usually the stage most often seen by the property owner.

Cat flea eggs are oval-shaped and only about 1/50 inch in diameter. Larvae that hatch from the flea eggs are about 1/20 to 1/5 inch long and look like a very small grub. The pupal stage has a silken cocoon that is prepared by the larvae and looks like it has a sticky outer surface of dirt and debris attached to the pupal covering. As one might expect, they are very difficult to see since the silk covering gives them a camouflaged appearance.

Behavior, Diet & Habit

The cat flea has a much wider range of hosts than most other flea species. Common hosts for cat fleas include dogs and cats, plus outdoor animals such as raccoons, opossums, skunks and foxes. This wide range of potential hosts is an important factor since sometimes homeowners that do not have pets may have problems with cat fleas that are located on the property or were brought inside the home from an outside source. Therefore, a problem for homeowners may occur when an infested wild animal occupies a chimney or a crawl space. However, the source of a cat flea problem inside the home is very likely a result of a pet being infested while roaming outside the home and then bringing cat fleas inside.

The cat flea’s life cycle is one of complete metamorphosis: an egg stage, larval (grub) stage, pupal (cocoon) stage and adult stage. The cat flea’s life cycle usually lasts from about 1 to 2 ½ months and depends on the temperature and humidity of their habitat.

Adults are the only stage that lives on the host, and the female adult cat flea must have a fresh blood meal in order to produce a new batch of eggs. After the female flea lays eggs on the host, the tiny eggs fall from the host onto locations such as carpets, pet bedding, behind or under furniture and inside cracks and grooves in the floors and, if outdoors, onto areas near where pets or wild animals reside. About two days after the eggs are laid, the larval stage hatches. This “worm-like” stage lasts about 5-15 days before the larvae become pupae. In general, the preferred places for larval development are locations that are protected, dark and where the relative humidity is at least 75 percent and the temperature is 70 to 90°F. Therefore, fleas do not survive outdoors in open, sunny locations where vegetation is kept mowed close to the ground and the lawn is “sun drenched” for example.

The pupal stage provides protection for the developing adult. Whenever the presence of vibration or an increase in host carbon dioxide and body heat occurs, the adult is stimulated to emerge from the pupal case. Upon emerging, the adult flea almost immediately hops onto a passing host and begins taking a blood meal within about 24-48 hours. This behavior explains why sometimes homeowners who own pets are greeted by hungry, hopping fleas upon returning home after a vacation or other extended absence. However, should the environmental conditions not be right for emergence, the pupal stage is extended for months or even longer before the adult emerges and seeks out a host.

Cat flea larvae do not consume blood; rather, they feed on almost any kind of organic debris that is located where they dropped. However, their main source of nutrition is dried adult fecal matter (“flea dirt”) that is made up of undigested, dried blood that falls from the host animal to areas where the larvae live.


Flea reproduction takes place indoors year-round, but outdoor reproduction is limited to warm-weather months and locations that fall within the preferred humidity and temperature.

Signs Of A Cat Flea Infestation

Since fleas are relatively easy to see in their adult stage, visible evidence is the obvious sign of an infestation. Some common signs of fleas on dogs and cats are “flea dirt” in the animal’s coat, seeing fleas on the less hairy portions of the body, excessive scratching, licking or biting at the skin and loss of hair.

Other signs of a cat flea infestation are the observable symptoms of flea bites on people. Such symptoms may include a red, swollen, itchy, but not painful, area that appears at the bite site about thirty minutes after the initial bite, a blister that occurs within two days of the bite and constant itching that causes the bite site to possibly bleed and lead to secondary bacterial infection.


The cat flea’s distribution is worldwide and is the most commonly found flea species within the United States.

More Information

Since the immature stages of fleas are very cryptic by nature, cat flea control is a job for your pest management professional and your veterinarian, if you have pets. While your veterinarian will advise you about using flea control and prevention products for your pets, your pest management professional will provide suggestions and advice for preventing fleas from getting inside your home; what to do if a non-pet animal is the source of the flea problem; and providing a scheduled, follow-up inspection to access the results of your flea control program.

Bites Can Transmit Disease
Cat fleas may transmit diseases in the process of taking a blood meal from a human or animal host or via infection from contaminated fecal pellets. Some of the more commonly encountered flea-borne diseases affecting people worldwide include:

  • Flea-borne typhus, also known as murine typhus – transmitted by the bacteria from feces of infected cat fleas when the bacteria enters the body at the time of the flea’s bite or from scratching the area of the bite.
  • Bartonellosis (cat scratch disease) – transmitted to humans from the bites of the oriental rat flea and cat flea.
  • Flea tapeworm – most often can be transmitted if children accidently eat an infected flea or contact infected flea feces.
  • If the bitten area is not kept clean and disinfected, secondary bacterial infection where bites occurred. The more that bites are scratched, the more likely infection will result.

Cat flea-borne diseases or other health-related conditions affecting pets can include:

  • Murine typhus from an infected flea bite
  • Cat scratch disease
  • Flea tapeworm – Dipylidium caninum. An infection of dogs and cats when they ingest a tapeworm infected flea during grooming.
  • Rickettsia felis, a disease of both cats and dog and transmitted by the cat flea
  • Dipetalonema reconditum, a parasitic worm transmitted to dogs by the cat flea
  • A microfilarial disease Acanthocheilonemal reconditum transmitted to dogs by the cat flea.