Fleas are found throughout the world and cause misery to humans and animals because of their irritating bites and ability to transmit disease. The species most commonly in the home is the cat flea, Ctenocephalides felis. Contrary to what the name implies, cat fleas infest both cats and dogs equally. Fleas can carry or transmit various diseases such as the bacterium that causes bubonic plague. Fleas often cause serious allergies to infested animals and humans.
The Flea Life Cycle
All fleas are associated with warm-blooded hosts because they provide 3 essentials for life - warmth, shelter and food. They pass through 4 developmental stages in their metamorphosis from egg to adult: egg, larva, pupa and adult. The most favorable conditions for egg hatching and flea development are 65° F to 80° F with a relative humidity of 70% or more. Dryness is fatal to larvae because they cannot close their breathing holes to retain moisture. Thus, hot, dry summers reduce flea populations and rainy summers produce larger populations. Temperatures over 95° F are also unfavorable. Tests indicate that cat flea larvae die after exposure to a temperature of 103° F for one hour.Under optimal conditions, a female can lay about 25 eggs a day, 3 - 18 at a time after each blood meal for at least 3 weeks. She can produce over 800 eggs during her lifetime. Eggs are laid either on the pet or off the pet where it sleeps. They are smooth, oval or rounded, light-colored and about 1/50 inch long. Although they are a little sticky, eggs laid on the host fall off and accumulate in bedding, floor cracks, rugs, furniture, dust and damp soil. Eggs hatch in 2 - 12 days. The "salt and pepper"-like stuff found where the pet has been sleeping is a mixture of flea eggs (white) and dried blood (black).
The hairy, worm-like, white or grayish larvae are 1/16 - 1/5 inch long and have distinct brown heads. They do not have eyes or legs. The larva go through 3 stages of development (instars) in 8-24 days. In unfavorable conditions, they may develop more slowly, taking up to 200 days. The larvae live wherever the eggs have fallen; they do not live on the pet nor do they bite pets or humans. They feed on various kinds of organic debris, such as lint, hair, and especially the dry bits of partly digested blood that adult fleas excrete.
In 1 week to several months, the larvae spin cocoons and transform themselves into pupae, which often become camouflaged among the debris. Under favorable conditions, the pupal stage lasts 5 - 10 days, but in adverse conditions it may last nearly a year. It takes a flea about 2 weeks to go from egg to adult at 95° F and almost 5 months at 55° F. Adverse conditions may be caused not only by weather but also by the absence of a host. Emergence takes place in response to host warmth and vibrations, as well as to carbon dioxide emitted from the host during respiration. Massive flea populations can result when accumulated generations of unhatched flea pupae are triggered to hatch by the presence of a host.
Once emerged, the male and female fleas immediately seek a blood meal with their piercing-sucking mouthparts. These adults are quite small (1 /10 inch long), black in color, and wingless. After feeding, they expand and appear lighter brown. Adults can live 1 - 2 months without a meal and can survive 7 or 8 months with one. Adult fleas have strong hind legs that enable them to jump onto hosts. Once on the host, they are able hitchhike considerable distances. back to the list
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