Pets and Your Health - Fleas

Fleas Infesting our Pets and Homes

What is a flea?

Fleas are small, wingless insects, flattened from side to side, that infest the hair coats of mammals or plumage of birds. Adult fleas have piercing mouthparts which they insert into the skin of their host to feed on blood. Worldwide there are more than 2,400 species of fleas. Luckily, only a few flea species feed on our dogs and cats with any regularity. This publication is primarily concerned with the cat flea, Ctenocephalides felis, which is by far the most common flea species found on both dogs and cats and in our homes. Control methods discussed in this publication are generally effective against any other flea species that may be occasionally found on our pets or in our homes.

Adult male cat fleas are only about 1 /12 to 1 /8 inch long (2 to 3 millimeters); blood-engorged females range up to 1 /5 inch long (4 to 5 millimeters). Newly emerged fleas are very dark brown. Thereafter, their colors are somewhat lighter. Actively reproducing females are light brown to orange.

How do fleas develop?
Fleas develop by complete metamorphosis. Like the butterfly, the life cycle of the flea involves an egg, larva, pupa (cocoon), and adult. The reproductive cycle of the female flea begins 24 to 36 hours after her first blood meal, when she lays her first egg. A female cat flea can lay as many as 40 eggs per day and over 2,000 eggs in her lifetime. Egg numbers vary because the reproductive capacity of the flea is dependent upon environmental and host-related factors, such as the extent of grooming activity by the host, temperature and humidity.

The immature stages. Flea eggs are pearly white, oval and the size of a grain of sand 1 /50 inch ( 0.5 millimeters ). The eggs are not sticky and easily roll off the fur of the host when laid. Flea eggs usually hatch in 1 to 10 days, depending on the temperature and humidity (humidity of 50 percent or less will desiccate eggs and larvae). Newly hatched flea larvae are slender, yellow, segmented, maggot-like and 1 /25 to 1 /12 inch long (1 to 2 millimeters). Larvae are free living and feed on organic debris found in their environment. They also feed on adult flea feces, which is partially digested dried blood. Once the larvae have ingested adult flea feces they become darker in color. Larvae do not like direct light. They move actively, deep among carpet fibers or under organic debris (grass, branches, leaves, or soil), searching for food. The larval stage usually lasts for 5 to 11 days, depending upon the availability of food and the climatic conditions. Temperatures below 65° to 70°F prolong larval development. After completing development, the mature larva, which is 1 /6 to 1 /5 inch in length (4 to 5 millimeters), moves to an undisturbed site to produce a silk-like

Newly emerged fleas are attracted to house pets by the warmth of the animals body, movement, changes in light intensity, and exhaled carbon dioxide. Fleas have tremendously powerful back legs, which they use for jumping onto their host. It has been reported that cat fleas can jump as high as 13 inches. When stimulated, the flea will jump toward the source of the stimulus and try to attach to a suitable host. It is these newly emerged fleas that are found in the carpet and most often bite humans before finding their preferred host (dog, cat, ferret, raccoon, opossum). The newly emerged fleas can survive for 1 to 3 weeks without feeding, but as soon as they are on a suitable host they will feed and mate, and females will begin egg production within 24 to 36 hours.

This page was updated on 23-Jan-2011