Ctenocephalides felis

Ctenocephalides felis is one of the few flea species that is truly cosmopolitan. In the United States, these fleas are ubiquitous in all areas except the mid- to north- Rocky Mountain area. Throughout the rest of the world, cat fleas are found wherever suitable hosts reside. (Hubbard, 1968; Roberts and Janovy, 2000; Swan and Papp, 1972)

Cat fleas live in the nests and resting places of their hosts when they are not feeding, and on their hosts when they are feeding. They live in just about any type of habitat, as long as it is warm and humid enough to promote development. (Roberts and Janovy, 2000)

Like all fleas, Ctenocephalides felis is laterally compressed and wingless. Cat fleas are 2 mm long and reddish-brown to black, with the females being a bit larger than males and a slightly different color. Aside from the slight difference in size and color, the other main distinguishing feature between males and females is the presence of complex, snail-shaped genitalia in males. Ctenocephalides felis is distinguished from other fleas by its characteristic ctenidia, or combs; it has a pronotal ctenidium and a genal ctenidium with more than 5 teeth. The morphology of cat fleas is similar to that of dog fleas, Ctenocephalides canis, but cat fleas have a characteristic sloping forehead. The hind tibia is also different from other flea species in that it lacks an outer apical tooth. All members of the order Siphonaptera have powerful muscles containing resilin, a highly elastic protein, in their legs, which allows these fleas to leap as high as 33 cm.

Flea larvae resemble tiny maggots with short bristles and mandibles for chewing. Pupae live encased in silky debris-studded cocoons. (Arnett, 1985; Hubbard, 1968; Roberts and Janovy, 2000; Swan and Papp, 1972)

The life cycle of Ctenocephalides felis is a holometabolous one; that is, it involves complete metamorphosis. The entire life cycle lasts from 30 to 75 days depending on environmental conditions. At 13 degrees Celsius, the larvae emerge from the eggs in 6 days. Lower temperatures and low humidity slow development. After going through three larval instars, or molts, larval fleas spin loose cocoons of silk and enter their pupal stage. The pupae are sensitive to fluctuations of carbon dioxide in the environment and also to vibration. When an appropriate change in either of these factors occurs, the adult emerges and finds a host on which to live. (Marquardt, 2000; Roberts and Janovy, 2000)

No information is available on the mating system of these fleas.

Flea eggs are fertilized internally. The adult females lay their eggs on their host, but the eggs soon fall into the host's nest, where they develop. The eggs are white, translucent, and approximately 0.5 mm in length. (Marquardt, 2000; Roberts and Janovy, 2000)

Female fleas carry their eggs inside of them, providing them with nourishment until they are laid. After they are laid, there is no further investment on the part of the parents. (Roberts and Janovy, 2000)

Optimal conditions for survival of Ctenocephalides felis are described by a temperature range of 26.7 to 31.5 degrees Celsius and a relative humidity between 50 and 92 percent. Given these favorable conditions and a steady food supply, fleas can survive for two to three years. (Arnett, 1985; Kern, et al., May 1999; Roberts and Janovy, 2000)

The cat flea is not a social species. In its adult form, Ctenocephalides felis spends most of its time in the sleeping area of the host, only jumping onto its host when it needs to feed. The genal and pronotal ctenidia help keep these fleas firmly planted on their host so that it is hard for the host to remove the fleas. The powerful muscles in the fleas' legs, specialized for jumping, allow them to remove themselves from their host at their own free will. (Arnett, 1985; Kern, et al., May 1999)

The pupae are sensitive to fluctuations of carbon dioxide in the environment and also to vibrations. They use these environmental cues to time their emergence from their cocoons. Fleas possess a sensory organ called a pygidium on the posterior portion of their bodies, which allows them to detect vibrations and air currents. No information is available on how these fleas communicate with one another. (Roberts and Janovy, 2000)

After piercing the skin of the host, adult cat fleas use their mouthparts to suck up blood. The bloodmeal then passes through epithelial cells in the gut that are elongated into spines, collectively called the proventriculus, where it is broken up. As their name implies, cat fleas prefer to feed on domestic cats, Felis silvestris. Cat fleas also feed on dogs, rabbits, horses, skunks, foxes, mongooses, koalas, and poultry. They are known to bite humans in the absence of other hosts. In contrast to adult Ctenocephalides felis, larvae feed on the feces of the adult cat fleas and detritus in the environment. (Dryden and Gaafar, July 1994; Peterson, 1951; Roberts and Janovy, 2000; Swan and Papp, 1972)

Ctenocephalides felis is an obligate ectoparasite whose main hosts are cats. Cat fleas also parasitize dogs, rabbits, horses, skunks, foxes, mongooses, koalas, and poultry. Cat fleas are vectors for murine typhus and intermediate hosts of the most common tapeworm that infects cats and dogs, Dipylidium caninum. They have been known to carry Burrelia burgdorferi, the spirochaete that causes Lyme disease. (Dryden and Gaafar, July 1994; Peterson, 1951; Roberts and Janovy, 2000; Swan and Papp, 1972)

Ctenocephalides felis is of some medical and economic importance. Most prevalent, but least serious, is the allergic reactions that fleas and their feces induce in some humans and animals. Itching and redness may occur, but with no serious results. Ctencephalides felis is a vector of murine typhus in humans, caused by Rickettsia mooseri. It is also the intermediate host of the most common tapeworm that infects domestic cats and dogs, Dipylidium caninum. It has been known to carry Burrelia burgdorferi, the spirochaete that causes Lyme disease, but it does not transfer the disease. All of these conditions require medical attention. The amount of damage in dollars per year is not available, but with the numerous variety of diseases that Ctenocephalides felis carries, the additive amount is not likely to be low.