University of Maryland Extension


Back to Insects - Stinging/Biting

close up cat flea
Photo: Joseph Berger, 

Adult cat fleas are about 1/16-1/8 inch long, brownish black and flattened from side to side. They are wingless but can jump considerable distances for their size. Female fleas lay 4-8 eggs after each blood meal. The eggs are laid on the host but fall off easily. The eggs are found in the pet's bedding or in areas where they frequent. Eggs are oval, whitish, and only about 1/64 inch long. They hatch in 1-12 days depending on temperature and humidity. Larvae are worm-like, whitish in color and about twice as long as the adult flea. They feed on organic debris including the dried fecal material from adult fleas. Larval development can take from 1-2 weeks to several months depending on temperature and humidity. When ready to pupate the larva spins a silk cocoon and incorporates debris to help camouflage it. The pupal stage may last 4-14 days under ideal conditions or up to a year under adverse conditions. Adult fleas may survive up to a year. The cat flea is the most common flea encountered in homes. It survives on both dogs and cats and will bite humans.

close up flea larva
Flea larva


Flea control in the home is important. The primary means of control is thorough vacuuming of floors and furniture and frequent cleaning of the pet's bedding. Carpeting and floors may be sprayed with products that contain the insect growth regulator methoprene which kills flea eggs and larvae. The trade names are Precor and Fleatrol. It is often sold in combination with an insecticide to control adult fleas. Growth regulators may last up to 210 days. Concentrate on areas where the pet frequents and sleeps. Do not walk on treated floors or carpets, or allow pets into treated areas until the spray has dried.

Use a flea comb on the pet to regularly remove adult fleas. Several flea control products are available from your veterinarian such as Advantage, Advantix, Frontline, and others. Check with your veterinarian to see which material is best for your pet.

Control Outdoors

Fleas are seldom an outdoor problem unless the pet spends all of its' time outdoors. Fleas prefer a protected, moist environment away from direct sunlight. However, spot treating of pet resting areas may be necessary. These areas may be treated with insecticidal soap or pyrethrin sprays. Also, either drying out or heavily watering of these areas kills eggs and larvae. If the pet is restricted to a fenced area, such as a dog run, it may be necessary to treat with an insecticide. Use methoprene that is labeled for outdoor use. Check with your veterinarian or pet supply store for availability and safety. Consult your veterinarian before treating with an insecticide.

Additional Resource

Publication: (PDF) HG 27 Fleas

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