Safer Flea Control

New products are making flea control easier and safer than ever. However, to be most effective, a careful plan of attack should include rigorous sanitation, pet treatment, premise treatment and follow-up.


Fleas are easy to identify. Look for small (1/8 inch-long), wingless insects in the fur of dogs and cats. Adult fleas are brown to black in color, with strong jumping legs. Adult cat fleas feed on dogs, cats, and a variety of furred animals. People may be bitten by fleas, especially when populations are high, but fleas will not live and reproduce on humans.


Flea control is best achieved through a four step process. Good sanitation, pet treatment, premise treatment and follow-up are all critical to good flea control.

Sanitation. Frequent vacuuming and disrupting of flea breeding sites can help greatly in indoor flea control. Fleas lay eggs while on the pet. Eggs then drop off the animal into carpet, bedding, furniture, or onto the floor. After a few days the eggs hatch into very small, legless larvae. Partly digested blood that flakes continuously from a flea-infested pet is the main food source for larvae.

Thorough vacuuming with a good, beater-type vacuum can remove 15-30% of larvae and 30-60% of flea eggs from carpeting. In addition, vacuuming helps remove some of the flea larva’s food supply and straightens carpeting fibers, enhancing penetration of the carpet by insecticide sprays.

When vacuuming pay special attention to areas where the pet spends a lot of time. These are the sites most likely to harbor eggs, larvae, and the dried blood that larvae need. Don’t neglect to vacuum under furniture, cushions, chairs, beds, and along the edges of walls–favorite flea breeding sites. Be sure to discard your vacuum cleaner bag at least once a week when battling a flea problem. Fleas can continue to develop inside a vacuum cleaner bag and can reinfest the house.

Pet Treatment. Your pet’s first defense against fleas should include a flea comb and a good bath. Soap in a pet bath acts as a gentle insecticide and will help control lighter flea infestations. Use of a flea comb, though time consuming, can also help reduce the need for insecticides. Flea combs are fine-toothed combs designed to help remove adult fleas from the pet’s fur. Most dogs and cats seem to enjoy combing. When combing pay special attention to the face and neck regions, and the area in front of the tail. Dip the comb frequently in soapy water or an alcohol solution to kill any fleas removed from the pet.

Heavier, or chronic, infestations are best treated by a veterinarian. Your veterinarian knows what can be safely used on your pet, and can supply you with materials for home treatment.

Tablets. Several new products are available in tablet form that provide effective and relatively safe treatments for most pets. Capstar® (nitenpyram) is a fast-acting flea killing product that eliminates fleas on an animal within 4-6 hours, but provides no residual control.  Comfortis® and the combination product Trifexis® (spinosad) are flea tablets for dogs only that provides similar quick control but last up to a month.

Insect growth regulators, or IGRs, are among the safest flea treatments. Growth regulators work by disrupting the normal development of flea eggs and larvae. Because IGRs mimic insect hormones (chemicals made by the insect itself, which appear to have no effect on people or pets) they are among the safest products on the market for flea control. Currently, IGRs can be applied to the pet via sprays, tablets or food additives that are given to the pet on a regular basis, usually once a month. One such veterinarian supplied IGR is Program®, with the active ingredient lufenuron. Lufenuron can be administered as a pill or food additive, or injection for longer term control. Sentinel® is another product that contains lufenuron plus a heartworm preventative. These products have proven effective, particularly on pets that live mostly indoors. Such products may be more expensive, however, than homeowner-applied treatments.

Methoprene is an IGR that is available through most pet stores as a spray for on-animal use. Methoprene is sold under several trade names including Precor® and vIGRen®. Methoprene is available in dip, pump spray, and in combination with other active ingredients. It has a long life on the animal’s fur, but does not kill adult fleas.

Because most IGRs only affect the egg and larval stage, and not the adult stage, they are commonly mixed, or applied in combination, with another insecticide that kills adult fleas. Allow 4-6 weeks to see significant reductions of flea numbers when using flea pills or other IGR treatments alone.

Other low toxicity, on-animal treatments that provide effective control include imidacloprid (Advantage® and Advantix®), dinotefuran (Vectra®), fipronil (Frontline®, PetArmor® and other generic versions), and selamectin (Revolution®). Most of these products act as nervous system poisons to kill adult fleas, but because of their inherently lower toxicity for mammals, pose little risk to pets or people. These products are generally superior to pyrethroid spot-on treatments and most pet collars.

Plant-derived, or botanical, insecticides kill adult and larval fleas and are relatively low in toxicity. Many are commonly sold over-the-counter. Botanical insecticides include pyrethrum (or pyrethrins) or citrus oil extracts (i.e., limonene and linalool). Once applied, these products break down in a relatively short time, leaving the pet with no residual protection against new fleas. Like all insecticides, these products should be used with care. When used properly they should pose little hazard to the pet or the applicator; however be aware that some cats may display sensitivity even to botanical insecticides, especially the citrus oil products.

Garlic, Brewer’s yeast, cedar bedding and various herbal collars and sachets are frequently promoted for flea control; however little scientific evidence exists to support such claims. Volatile oils in fresh cedar chips do have some insecticidal action against fleas, however the effective life of such chips is probably short. Brewer’s yeast has been tested and has not been shown to provide any protection to pets from fleas.

Premise treatments. While on-animal IGR treatments may reduce the need to treat your home, premise treatments applied to indoor or outdoor flea breeding sites are sometimes necessary. Ideally, premise treatments should be made at the same time as when the pet is treated. This is particularly important if pets have been treated with products that last only a short time.

Several good, low-toxicity treatments are available for indoor use. Citrus oil-based sprays containing limonene or linalool can be applied to rugs, carpeting, and pet bedding. These products act as contact poisons, killing only what they hit. After application they evaporate quickly, leaving a pleasant citrus smell, but little residual protection against emerging fleas. Follow-up treatments are usually necessary when using these and other botanical sprays, like pyrethrins.

Boron-based products, such as disodium octaborate tetrahydrate, are also available for flea control on indoor carpeting. Chemically similar to boric acid, these chemicals have little skin (dermal) toxicity to people or pets. When ingested by larvae scavenging for food in carpets, borates kill immature fleas. Because adult fleas feed on fresh blood only, boron insecticides do not control this life stage. Dustiness, abrasion to carpets, and contamination of furniture or food preparation surfaces are potential concerns with carpet-applied dusts. Shampoo-based boron formulations, applied wet to the carpet, may help minimize such problems.

Insect growth regulators that can be used for premise treatment include methoprene and pyriproxifen. Because it breaks down quickly when exposed to direct sunlight, methoprene is primarily used as an indoor spray. Pyriproxyfen sprays are more stable outdoors and are available through pest control operators under the name Archer® or Nylar®. Pyriproxifen is different from most other IGRs in that it controls both immature and adult fleas.

Diatomaceous earth, sometimes promoted as a safe flea control, is unlikely to provide practical or satisfactory flea control outdoors, based on laboratory evaluations at Texas AgriLife Extension. Diatomaceous earth acts as a dessicant (drying agent) and only works well in dry environments.  Mixing diatomaceous earth with water and applying as a spray appears to negate the ability of the dust to be picked up easily by fleas.  It can be useful in killing flea larvae, however, when applied as a dust to dry sites, such as pet houses and pet bedding.

Insecticides for use outdoors include the IGR pyriproxifen and several pyrethroid insecticides, such as permethrin and esfenvalerate.  Outdoor flea control can be enhanced by applying pesticides only where flea larvae are most likely to live. Outdoor spray treatments should focus on crawl spaces, bedding areas, sites under decks and shrubbery, and shady areas wherever your pets spend a lot of time. Well maintained lawns in sunny sites are unlikely to harbor many fleas.

Follow-up. Follow-up is especially important for flea control. The flea pupa is the intermediate life form between larval and adult life stages. The pupal stage normally lasts 7-14 days, but can persist for much longer under certain conditions. The pupa is normally well-protected from the effects of pesticide sprays and is very difficult to kill with insecticides. Fleas that are in the pupal stage when insecticides are applied, frequently survive treatment to emerge several days later. Hence follow-up treatments are usually needed. Two or more follow-up treatments with pyrethrum or a citrus oil-based spray (or a standard insecticide, if you wish) should be applied 5-10 days after the first application.

Don’t wait until fleas get out of hand to begin your flea control program. Start a frequent and thorough sanitation program, regularly inspect your pet for fleas, and carefully follow the label directions of whichever product you choose.

For more information

For more information on the latest in flea control safety issues, see the Protecting Pets page sponsored by the U.S. Environmental Protection Agency.  The Companion Animal Parasite Control website is an industry sponsored site with information on all kinds of parasites affecting pets.  Help with additional questions about fleas or other pests, can be obtained by contacting your county Extension office.


Michael Merchant, Ph.D., Urban Entomologist, Texas AgriLife Extension Service

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