(Figures 5-71 through 5-76)

Fleas are laterally compressed insects that have been the bane of humans and their animal companions for eons. Fleas suck blood from their feline hosts and are capable of taking enough blood to cause severe anemia that in kittens can induce cardiomegaly (King, 1997; Yaphe et al., 1993). The major flea of importance to the cat is the species Ctenocephalidesfelis. Several species and several subspecies of these fleas will bother the cat around the world (Ctenocephalidesfelisstrongylus in Africa and Ctenocephalidesorientis in the Orient and Oceania), but by far the most important parasite of the cat is Ctenocephalidesfelisfelis. Cats will sometimes fall prey to infestation with fleas from other hosts such as rabbits or rodents, e.g., infestations with Cediopsylla or Spilopsyllus, but typically cats are host mainly to the cat flea. On rare occasions, cats will also become infested with Echidnophagagallinacea, the stick tight flea of poultry.

Ctenocephalides: The biology of the cat flea, Ctenocephalidesfelis, has been reviewed in detail in recent years as more new information has been brought together on its biology (Rust and Dryden, 1997). Georgi and Georgi (1992) did an excellent job of presenting images that allow the easy recognition of the species and subspecies of importance. The adult fleas in this genus have both genal (cheek) and pronotal (neck) combs, i.e., thick bristles that give the flea the appearance of having a very thick mustache (Fig. 5-71). Adult fleas (Fig. 5-72) remain on their feline host if at all possible. However, some cats are excellent groomers and can easily remove 50 to 100 fleas in a twenty-four hour period. While on the cat, the adult fleas suck blood. A large portion of the blood imbibed by the fleas seems to pass directly through their system, female fleas make helices and males make small spheres. In both cases, the blood passed through the flea will dry and along with other detritus forms the basis of “flea dirt” that is found on a cat or under where an infested cat will usually rest. It appears, that what the adult fleas are actually doing is in part providing a dietary supplement for their offspring who will develop and feed in the material dropped where the host usually rests.

Two days after a male and female flea take up residence on a host, the female flea produces about 15 ovoid white and waxy eggs each day that do not stick to the hair coat but fall to the ground (Figs. 5-73 & 5-74). About two days after an egg gets to the ground, a first-stage caterpillar-like larva hatches by cutting through the eggshell with a structure that is analogous to the egg-tooth of birds and reptiles. The larva then eats and grows, and as long as the humidity does not get too low nor the tmeperature too cold, development will proceed (Fig. 5-75). The dark intestinal tract of the larva can often be viewed through the cuticle of the larvae; the dark appearance of the gut being due to the ingested flea feces that has been produced by the adults still on the host. After a period of about a week, the flea larvae will have molted twice to become a third-stage larva. This stage will then spin a silken cocoon that attracts bits of snad particles and other detritus that serve to protect it and conceal it within the environment. About 15 days after the eggs are laid, the adult fleas will begin emerging from their cocoons and be in search of a host. Adult fleas will emerge spontaneously from the pupal cases, but they can also be induced to eclose by the application of warmth and increased humidity, which would represent the resting of a cat upon a blanket.

During the past few years the development of new flea control products, i.e., lufenuron, fipronil, imidocloprid, and selamectin, have given the veterinarian, pet, and client a major respite from flea problems. These products all work to provide the pet with long-term protection that is very safe. They differ in their method of application and in the mode of action as to how the fleas are killed, and this allows for designing flea-control programs that fit the lifestyle and needs of certain pets and owners. A major concern is that resistance to these products will develop taht will make them less efficacious in years to come. Only time will tell, but it argues that people should not forget to work to maintain an environment where fleas do not thrive, i.e., dry and regularly cleaned with a vacuum.

Echinophagagallinacea. This flea has been recovered form cats on more than a few occasions (Georgi and Georgi, 1992; Coman et al., 1981). These fleas differ form the regular “cat” flea in that the adults embed their heads into the skin of the host while they feed. The adult fleas differ from Ctenocephalides in that there are no combs, and the dorsally compressed thorax gives the flea a humpeup appearance. These fleas are found mainly in the tropics and subtropics. The pathology associated with these fleas is not so much loss of blood and anemia, rather it is the reaction to the site of attachment.


Coman B.J., Jones E.H., Driesen M.A. 1981. Helminth parasites and arthropods of feral cats. Austral Vet J 57:324-327.

Georgi J.R., Georgi M.E. 1992. Canine Clinical Parastiology. Lea & Febiger, Philadelphia, 227 pages.

King J.M. 1997. Anemia caused by flea infestation in a cat. Vet Med 92:692.

Rust M.K., Dryden M.W. 1997. The biology, ecology, and management of the cat flea. Ann Rev Entomol 42:451-473.

Yaphe W., Giovengo S., Moise N.S. 1993. Severe cardiomegaly secondary to anemia in a kitten. JAVMA 202:961-964.

Figure 5-71. Ctenocephalidesfelis. Anterior end showing the genal and pronotal combs.

Figure 5-72. Ctenocephalidesfelis. Adult male.

Figure 5-73. Diagram of the life cycle of the cat flea. The adult fleas live on the cat and produce eggs that fall to the carpet or the soil. The eggs hatch and produce a larva. The larva crawls about in this environment and feeds. The larva undergoes two molts while growing, and it is the third-stage larva that ultimately spins a silken cocoon. The cocoon is sticky and will incorporate fibers and particles from the surrounding environment. The fibers and particles serve to help hold the cocoon in place and to camouflage the pupal case. The flea can remain in the pupal case after it has developed to the adult stage for an extended period. The flea in the pupal case is able to sense changes in the external environment, and adult fleas will eclose when they sense the presence of an appropriate host.

Figure 5-74. Ctenodephalides felis life stages. In this image are the white ovoid egg, two third-stage larvae, and a pupa that does not have any attached fibers or particles.

Figure 5-75. Ctenocephalidesfelis. Two larvae that have dark intestinal tracts visible through their body walls. The dark color is due to the ingested blood that is shed in the form of feces by the feeding adult male and female fleas.

Figure 5-76.Echidnophagagallinacea. Adult female.