Practically all warm-blooded animals are subject to attack by fleas. Each species of flea, however, usually feeds on a limited number of specific animals. Flea bites cause a persistent, annoying itch. Although some fleas, especially rat fleas, may transmit disease such as endemic typhus and bubonic plague, most fleas are not vectors. Fleas continue to feed and breed throughout the winter but often do so at reduced rates.
Females mate and lay eggs on the host from which a blood meal is taken.
Eggs typically fall off host animals and hatch in 2 to14 days. Outdoors in lawn areas or pet quarters, larvae generally feed on excrement from adult fleas, rodents, and domestic pets. Larvae also survive well indoors on organic debris in carpeting of overstuffed furniture. Under favorable conditions, a new generation of adults emerges 1 to 3 weeks later. An entire life cycle may be completed in just 2 or 3 weeks, but several months to 2 years may elapse if conditions are unfavorable.