(Portions of this article taken from a June 2000 article on fleas written by Nathan Riggs for the Bexar County Employee Newsletter)

Treating Fleas on Animals and in the Landscape

Fleas are small black insects that use warm-blooded animals for a host. The most common flea species found in South Texas is the cat flea (Ctenocephalides felis). Female fleas are the most active because they need the host's blood to produce eggs. The common cat flea is found worldwide on cats, dogs, rats, mice, raccoons, opossums, skunks, deer and other mammals. The cat is the flea's best host with dogs running second. Humans are bitten by cat fleas but are not a good host. One female flea can produce 24 to 36 eggs per day and may live for 60 to 90 days. Flea eggs are not sticky and fall off of the host after they are laid. When trying to control fleas, it is important to remember this important part of their life cycle. The highest numbers of eggs are deposited in areas where the host lies around. In and around the home, this could be furniture, flower beds, kennels, and sunny areas with bare, moist soil.

The eggs hatch into small caterpillar-like larvae that live in the soil, the animal's bedding, or at the base of the carpet pile. The larvae feed on bits of skin, left over food, and bits of dried, undigested blood that are excreted by the female fleas as they feed on the host. When they are fully grown, the larvae spin a sticky, silken cocoon, much like a moth, and change into the adult form. Cocoons in soil will be covered with soil; in carpet or on furniture they will be covered with fibers, hair and bits of debris. Cocoons are very difficult to see unless one is looking for them. Fleas in the cocoon can be dormant for up to 4 or 5 months if suitable hosts are not present. Therefore, if there is a flea problem in the home, and the owners leave for an extended period of time, fleas will emerge from their cocoons when they feel the vibrations of the returning owners' footsteps on the carpet.

Flea control must be addressed in two parts: on the pet and off of the pet. There are many methods for treating fleas on pets. The easiest and most effective are the formulations that are applied once monthly to the pet's neck. They are effective for 28 days and circulate in the pet's bloodstream. Other methods include collars, dusts, sprays and dips. Most of these wear off after a short period of time.

Off of the pet, treatment must be concentrated in bedding, sunning, and resting areas. This is where the fleas are breeding. Treating the entire area (outside or inside) for fleas may only be necessary for the initial application. Subsequent applications should only go on the areas mentioned before. Sprays and granules containing, diazinon, chlorpyrifos (Dursban™), permethrin, deltamethrin and pyrethrins as active ingredients are going to provide the fastest control, but should be reapplied about 3 weeks after the first treatment. There are many other tales of using plant materials like herbs and garlic against fleas, but there isn't any scientific data to support them.

One non-chemical means of controlling fleas comes in the form of a product that contains beneficial nematodes. Nematodes are microscopic soil worms that have been known to attack white grubs, crickets, and fleas. They can be purchased from nurseries and similar outlets, mixed with water and sprayed on the breeding areas. In order for the nematodes to survive, the soil must remain relatively moist and watered at least twice weekly. Beneficial nematodes do not harm plants, animals, humans or birds...just soil insects. Check with your local nursery or garden soil dealer and ask about beneficial nematodes.

For more information on fleas, read Texas Extension publication #L-1738 on controlling fleas.

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