Fleas are one of the more important groups of insect pests because they not only cause discomfort by biting, but they can transmit several diseases such as plague and murine typhus. Cat fleas are found throughout the United States and the rest of the world.

Adults are about 1/8" (2.5 mm) long. The body is laterally flattened (side to side); wingless. Color is brownish black to black, but is reddish black when full of blood. The female's head is twice as long as high. The compound eyes are well developed. Both genal and pronotal combs are present, each composed of 16 spines, and the genal comb's first 2 anterior spines are of about equal length. The femur of the hind leg has 7-10 bristles on the inner side. Abdominal terga (dorsal plate of segments) are 2-6 with a single row of bristles. In addition, antennae are short and 3-segmented; ocelli are lacking; legs are long, coxae are large, tarsi is 5-segmented; they are usually jumping insects; mouthparts are piercing-sucking with well-developed palps.

Mature larvae are about twice the adult length (1/4"/3-5.2mm). Larvae are whitish, slender, eyeless, and legless, with a well-developed head.

Females lay 4-8 eggs after each blood meal, laying some 400-500 during their lifetime. The eggs are not glued/stuck to the hairs or body but are deposited on or between hairs, or in the nest or bedding material. Hence, eggs deposited on the animal either fall or are shaken off, and are frequently found in cracks and crevices where pets sleep or frequent. Eggs are oval, whitish, and about 1/64" (0.5 mm) long. They usually hatch in 1-12 days.

It is not necessary to have pets in the building in order to have fleas present. Since fleas can jump about 6" (15 cm) vertically, they can easily hitch a ride on shoes, trousers, etc.

Fleas are typically found where animals sleep or frequent, including along their usual avenue of travel, because this is where eggs and adult fecal blood accumulate. Most larvae will be found in similar places but especially in areas with high moisture which is necessary for their survival. Pupae will be found in the same situations as larvae. Such places include both indoor and outdoor situations. Cat fleas are also found on other urban hosts such as opossum, fox, mongoose, and occasionally rats.
Flea larvae die at relative humidities below 45% and above 95%, and hence, are rarely found outdoors in arid climates. Larvae fail to develop at temperatures below 55 degrees F (13 degrees C) and at or above 95 degrees F (35 degrees C).

Information compiled from the National Pest Management Association, Inc. (NPMA)