Causes of Fleas

Fleas Are A Normal Part Of Your Yard Ecosystem
Besides cat and dog fleas, there are fleas that commonly infest squirrels, chipmunks, rats, birds, rabbits, and mice. Some of these fleas are not too choosy about which animal they live on, but they rarely attack people. They commonly live in animal burrows and bird nests. Flea larvae need a relative humidity of at least 50% to develop properly. Even if the relative humidity of the ambient air is not this high, it could be much higher in the microhabitat of a burrow or nest. Flea larvae can also survive short exposures to below-freezing temperatures.

Conditions That Foster Fleas
Outdoors, fleas are most abundant during humid, rainy summers and are more common outside in the southern United States than in the north. Outdoor flea populations normally are restricted to the areas immediately surrounding the host animal’s activities. Eggs and larvae are preyed upon by spiders and ants living in healthy home landscapes that host a diversity of plants and wildlife. However, where there has been frequent use of broad-spectrum insecticides which kill insects indiscriminately, nature’s first line of defense--the beneficial insects--is eliminated along with the fleas. Because pest populations rebound faster than those of their natural enemies, the fleas may reestablish themselves unmolested.

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