Fleas, and watch those insecticides!

By John Fulton              

[AUG. 21, 2006]  Flea numbers have "jumped" over the past two weeks. It is actually common to see large numbers of fleas as we get to August and September. What starts as a few fleas, grows rapidly during the heat of the late summer. Several killing frosts will put an end to much of the outdoor population, but fleas that are on animals or have made their way indoors are a different matter.

Fleas are small, pinhead-sized insects that are dark brown to almost blackish in color. They do not have wings but jump to get from place to place. Only adult fleas feed on blood. Although fleas will feed on people, causing red spots that look like mosquito bites on the lower legs and other areas of the body, they will usually not bother people if dogs, cats, mice or any wild animals are present.

Flea eggs hatch 10 days after they are laid, producing slender, whitish, wormlike larvae. These larvae feed on debris in carpeting, upholstered furniture and pet bedding. Fully grown larvae enter a short pupae stage, followed by the adult stage that feeds on blood. The entire life cycle, from egg to adult, takes about six weeks in the home.

Pet owners who have fleas on their pets can usually eliminate these insects by treating their pets weekly with a flea and tick powder for at least six weeks, using one of the newer generation topical treatments, or flea collars may also be used.

Here is the main caution when treating areas and animals. Pyrethrin-based products, such as flying and crawling or household insect aerosol sprays, can be used to eliminate the fleas, but there is an extreme toxic effect of this group of chemicals on dogs and cats. Directly treating a cat for fleas with permethrin can send the cat into shock and may result in its death.

Carbaryl (Sevin dust) is available and labeled to treat pets and their living quarters safely.

Read the label. If a product does not say it can be used on dogs or cats, it shouldn't be. Under the precautionary statements on the label, most of the pyrethrin and pyrethroid insecticides actually prohibit their use on pets.

Most treatments do not kill the eggs and pupae of the fleas, so three times at two-week intervals are needed to eliminate the fleas.

Infested lawn areas can be treated with an insecticide to reduce the chances of your home being reinfested. Spray any area where fleas appear to be present, particularly tall grass areas and areas where pets or wild animals tend to rest. Remember the safety issue of the pyrethroids versus carbaryl. The pyrethroids include permethrin, bifenthrin, fenvalerate, cypermethrin, resmethrin, tetramethrin and just about anything else that ends in an "in."

In summary, there is a toxicity that can cause death in pets (cats in particular) from treatment with pyrethrin and pyrethroid insecticides. Usually this is from direct application, such as trying to kill fleas on the animal. Fleas can be a definite problem this time of year, but there are other control options. Get animal products recommended by your veterinarian. Also, carbaryl dust insecticide is much safer for animals and can be used in bedding areas, lawns, etc.

Good luck in your battles against the fleas, and remember to keep your pet safe.

[John Fulton, unit leader, University of Illinois Extension, Logan County Unit]