Cat Fleas

Pest Facts: Fleas

Fleas are obligate blood-feeding ectoparasites mainly of mammals which belong to their own Order of insects, the Siphonaptera. There are about 2,500 different named species, but no more than about 20 species are common or widespread biting pests of people, pets or companion animals. By far the most common urban pest flea in North America is the Cat Flea, Ctenocephalides felis (Bouche). They are usually the species found pestering dogs and humans, not just cats, as their common name implies. This species is fairly typical and will be used here as the example for discussing the general biology, behavior, habits, and control strategies for all urban pest fleas.

Pest Facts
  • Color: reddish brown
  • Legs: 1-2 mm
  • Shape: Oval
  • Size: 1.5-3.2mm
  • Antennae: Yes
  • Flying: No
  • Region: US

Fleas have a complete life cycle including an egg, three larval stages, a pupal stage, and an adult (male or female) stage. Eggs take one to12 days to hatch; larvae require one to two weeks to develop through their three stages (instars); and pupae usually need four to 14 days to develop into adults. Under harsh conditions, the pupae can go into a diapause state and require nearly a whole year to complete development. Fully developed adults (within their pupal cocoon) have been reported to delay emergence for up to 20 weeks. In good conditions of 55 to 80 percent relative humidity (RH) and about 60o to 90o F (15o to 32o C), one life cycle can be completed from egg to adult in 15 days, but usually takes closer to three weeks (21 days). Under marginal conditions, one generation can often require at least 40 days; and could take as long as six months to be completed. After a long diapause period, new adult fleas can be stimulated by vibrations (like a host walking nearby) to quickly emerge from their cocoon and very actively seek a blood-meal host. Adult cat fleas can jump six inches (15 cm) or higher vertically, and they crawl very rapidly toward a suitable feeding spot once they make contact with a potential host’s fur or clothing. Cat flea larvae will die if they are kept in moisture levels of less than 45 percent RH, or more than 95 percent RH; and they will not develop at temperatures below 55o F (13o C) or above 95o F (35o C).


Pets (dogs/cats). It may not be necessary to have pets (dogs or cats are the usual suspects) in or near any given building to have cat fleas (or other flea species) present. Fleas can readily be carried from infested places into formerly uninfested settings on shoes, pant legs, or blankets. Many species of fleas will readily feed and survive well or alternate hosts if their primary hosts suddenly die, are removed or excluded, or leave. Cat fleas are often found in urban settings infesting various urban wildlife; especially opossums, raccoons and skunks. On many occasions, more than 20 adult cat fleas have been removed from a single live-caught adult opossums or raccoons. Larval cat fleas can develop well in the dens of such wildlife which are under, or next to, a house.

Prevention & Treats

Control measures include drops or pills administered to the animal. These products may be purchased from the vet or over the counter, depending on the product. The active ingredient varies but may include imidacloprid, permethrin, lufenuron, fipronil, and methoprene. These products go by the trade names of Front Line, Front Line Plus, Program, Advanced Care and others. Flea collars are also commonly used with varying degrees of success. Due to marketing, registration pressures, and other factors flea control products including shampoos will vary in availability.


*Resource credit: Courtesy of the National Pest Management Association*