Adult fleas are about 1/8-inch long, reddish-brown colored, wingless and have three pairs of legs. Adults are flattened side to side, a characteristic that enables them to easily move between the hair and fur of their hosts. Adults also have a row of spines on the front of their head that are useful for identification of various flea species. Fleas possess piercing-sucking mouthparts that adults use to inject into the skin of their host and then suck up the host’s blood. Flea larvae are about ¼-inches long, whitish colored and are grub-like and legless in appearance. Flea pupae are surrounded by a silk-like cocoon that is normally covered in particles of debris found in their surroundings.


Fleas are categorized into two major groups – nest fleas and host fleas. Nest fleas spend their life living in the nest of the animal they feed upon and will venture to their host only when needing to take a blood meal. Host fleas, on the other hand, spend their life on the host getting blood meals and shelter from living on the host. In general, nest fleas choose to live in rodent and bird nests, while host fleas will live on practically any mammal from which they get a blood meal.

Contrary to popular belief, adults are the only stage that directly consumes a host’s blood, and adult fleas must eventually take a blood meal in order to survive and produce viable eggs. But, in the absence of a host, adult fleas may live about 2-12 months without feeding.

Adult female fleas that have taken a blood meal lay eggs on the host’s fur. After a short time period, the eggs that she laid will drop off the host and land almost anywhere the host has been. After dropping from the host, the eggs hatch and the resulting flea larvae seek out protected locations for continued development. Examples of such indoor locations are cracks and crevices along baseboards, under the edge of carpets, and behind furniture or beds.

Flea larvae spin a silk-like cocoon in which they develop into flea pupae and where pupae become pre-emerged adults that may reside in the cocoon as inactive adults for weeks or even months while awaiting a host.  Field researchers have observed cat flea pre-emerged adults living inside the cocoon for up to five months before becoming active when they sense the heat, carbon dioxide and vibrations caused by a host’s movements. This phenomenon explains why people and pets who are away from the home on an extended vacation, or when people move into an empty house that is infested with fleas, walk into a situation where it seems that the house has suddenly “come alive” with hungry, biting and pestiferous adult fleas.


Adult fleas feed on blood from birds and mammals such as cats, dogs, rodents and urban wildlife such as raccoons, opossums and skunks. Larvae feed on adult flea feces (flea dirt), which is largely composed of undigested blood. Also, larvae will feed on dead skin, hair, feathers, and other organic debris. About 95% of adult fleas get their blood meals from mammals, while only about 5% of adult fleas take a blood meal from birds. Flea pupae do not feed.


Inside the home or building, fleas are likely to be concentrated in locations where pets or other hosts sleep and spend a lot of their time. Outdoors, fleas are likely to be concentrated in locations where their hosts nest, roam for food, sleep, rest under shrubs. Preferred flea habitats can also be in an attic or crawl space, plus locations that are protected from open sunlight and dry conditions.


Fleas develop by complete metamorphosis and, depending upon the flea species, temperature, and humidity of its surroundings, may take from two weeks to eight months to complete the life cycle. Adult female fleas lay from 15-20 eggs per day and in a lifetime will lay up to about 600 eggs. Eggs hatch in about 10 days and the larval stage can last from as little as a week to upwards of several months. In an environment of plentiful hosts, the pupal stage may last for only about 5-14 days. However, in the absence of a host, the flea’s pre-emergent adult phase remains in the pupal case if a host is not present to stimulate an adult flea to leave the protective pupal case and take a blood meal.


Since adult fleas are relatively easy to see, visible evidence is the most likely indicator of fleas. Other signs are “flea dirt” (feces) in a host’s fur, excessive scratching, biting at the skin, hair loss, rash and flea bites on pets or occupants of the home.


For many homeowners, prevention centers on effective care of their pets. Some of the useful things to do include:

  • Regularly bathing and grooming pets.
  • Frequently laundering pet bedding or items they rest on. Always use the hottest setting of the washer and dryer.
  • Vacuuming areas where flea larvae and pupae may be located.
  • Steam cleaning carpets.
  • Keeping the lawn open to as much sunshine as possible, keeping grass closely trimmed, and fencing the property to keep other animals from bringing fleas into the yard.
  • Controlling rodents and other flea hosts.
  • Keeping animals out of your attic and crawlspace.


Flea control is an integrated process that includes the following methods and materials, plus the items listed in the section above:

  • Contact your pest management professional and request an inspection and flea management plan. Much of the time, this is the best way to obtain safe and effective flea control.
  • Use treatments and products for flea control on your pets (spot-on treatments) that are recommended by your veterinarian.
  • Use pest control materials in the house and yard at the same time you take your pet(s) to the veterinarian for treatment. Often, treating only a pet does not do much to reduce the numbers of flea larvae or adults that are present elsewhere.
  • Use insect growth regulators as part of the flea control effort.