Least-Toxic Control of Fleas Choose a different pests

Factsheet: Least-toxic Control of Fleas


Pest type: Insects

In-depth Information:
Adult fleas are about 1/16 to 1/8-inch long, dark reddish-brown, wingless, hard-bodied (difficult to crush between fingers), have three pairs of legs, with enlarged hind legs for jumping, and are flattened side to side allowing easy movement between the hair, fur or feathers of the host. Fleas are excellent jumpers, leaping vertically up to seven inches and horizontally thirteen inches. (An equivalent hop for a human would be 250 feet vertically and 450 feet horizontally.) They have piercing-sucking mouthparts, spines on the body projecting backward and a row of spines on the face. Eggs are smooth, oval and white. Larvae are 1/4-inch long, slender, straw-colored, brown headed, wormlike, bristly-haired creatures. They are legless, have chewing mouthparts, are active, and avoid light.

Is it a problem?

Fleas can become a problem regardless of whether or not there are pets in the building. They can be brought in on the clothing of staff, students or visitors, or become problems from urban wildlife lining in unused parts of the buildings, such as rats, feral cats, raccoons, opossums, chipmunks, squirrels, or birds. Flea bites cause irritation and serious allergies in animals and humans. Cat fleas, less commonly, can carry and transmit organisms causing the bubonic plague, murine typhus and the double-pored dog tapeworm, which can live in dogs, cats and humans.

Pest prevention practices

Remove potential habitat

Seal up cracks and crevices both in and outside of buildings that may harbor flea larvae. 

Block off all entrance points in buildings that may invite wildlife habitation. 

Vacuum daily with a strong vacuum cleaner, changing the collection bag often.

Bathe pets frequently with soap and water. Restrict pets to a single bed, washing the bedding frequently to kill larvae and adults.

Monitoring and record-keeping

  • Detection can be as simple as seeing fleas or noticing bites around the ankles of people in the building. Flea dirt, the adult flea feces that dries and falls off the host to serve as food for larvae, may also be visible. Monitor in and around the cages of pets, the pets themselves for signs of fleas, and places where animals may find shelter, such as basements, crawl spaces, attics, eaves, roof top structures, and secluded shrubbery near buildings. 
  • Traps can also be used to detect flea populations. Flea Sock Traps are homemade, knee-high, white flannel booties that fit over the shoes and lower pant legs, as well as make a fashion statement. When walking through flea-infested areas, fleas will jump onto the flannel and become tangled in the nap. You can easily see and count them to determine the degree of infestation. 
  • In a pinch, long, white athletic socks worn over shoes and pant legs will work, as will wide strips of sticky-backed paper wrapped sticky-side-out around the lower legs.
  •  Light Traps are compact traps composed of a small electric light and a sheet of sticky paper. Adult cat fleas may be attracted to the warmth and light of the trap, hop over, and get stuck on the paper. Fleas are more sensitive to green light, and are more attracted to light traps if the light is turned off for 10 seconds every 5 or 10 minutes. The light trap should be checked once a week. 
  • If no fleas are caught by the second week, move the trap to another location or remove it. If only a few fleas are caught, the infestation is very small and can probably be controlled by the traps alone, and the traps should be left in place until no additional fleas have been caught for a week. If 20 or more fleas are caught in a week, there is probably a more serious infestation, and it is time to find the source.

Non-chemical and mechanical controls

Seal cracks and crevices
Repair holes
Remove water source: check drains, faucets and pipes
Remove standing water
Steam treatment
Sanitation — use soap and water to clean surfaces

Restrict pets to a single bed, and wash this frequently. Also try sprinkling the bed with pine needles, rosemary, fennel or rye.

Groom pet with a flea comb daily. After each stroke, check for fleas caught in the comb, picking off and dumping any in soapy water. Pick off any fleas from the comb and dump into soapy water.  

Give pets vitamin B1, shown to reduce flea bite frequency. A small dose of brewer’s yeast should do. A better option might be to go to the veterinarian for a B-complex vitamin supplement.

The same light traps mentioned above are effective for flea control, using either sticky paper or a small tub of soapy water to catch attracted fleas.

Biological controls

Nematodes applied to the lawn as a spray enter the fleas’ bodies, feeding on tissue and releasing harmful bacteria. They do not affect people, pets or plants, and occur naturally in soil, so they will not adversely affect beneficial soil organisms. Use the number of nematodes recommended by the manufacturer; treat areas where you have found evidence of flea infestation, animals sleeping, or regular travel routes for animals; and water the area before and after the application.

Least-toxic chemical options as a last resort

  • Diatomaceous earth or silica aerogel is effective flea control when applied in a light dusting to upholstered furniture that is suspected of harboring fleas (especially in cracks and crevices), rugs or pet bedding; applied to infested carpets, left for a couple of days and then vacuumed up; and sprinkled in crawl spaces, wall voids, attics and other spaces where animals may be nesting or sleeping. Do not use in moist environments. Choose a desiccating dust that it is not combined with a pyrethrin. Diatomaceous earth must be food grade, as swimming pool grade is associated with lung disease. Desiccating dusts abrade the outer shell of the fleas, causing them to dry out and die. Avoid breathing in desiccating dusts, as they can cause lung irritation, and always wear a mask and goggles when applying.
  • Boric acid worked into the nap of carpet can be used to control fleas. It works as a “stomach poison” for fleas and will remain viable for up to a year. Exercise caution when using products containing boric acid, and do not use it in areas where children or pets will come in direct contact with the chemical.
  • D-limonene and linalool are citrus extracts that have proven effective for flea control. Products containing d-limonene kill larval and adult fleas, while those containing both ingredients kill eggs as well. There are EPA-registered shampoos containing these ingredients, but read the label carefully, as some are too strong for cats or young animals. Limonene is listed as a volatile organic compound (VOC) by the EPA, which can be associated with irritation, odors and other health and comfort concerns. Those with existing sensitivities should be extremely careful when using a product containing limonene, or consider using another alternative.

Boric Acid

Cinnamon Oil

Citronella Oil

Clove oil


Garlic oil


Peppermint Oil

Chemicals to Avoid

Look at your product labels and try to avoid products containing those chemicals listed below:

(A = acute health effects, C = chronic health effects, SW = surface water contaminant, GW = ground water contaminant, W = wildlife poison, B = bee poison, LT = long-range transport)

Bifenthrin (A, C, SW, W, B)

Carbaryl (A, C, SW, GW, W, B)

Cyfluthrin (A, C, W, B)

Cypermethrin (A, C, W, B)

Deltamethrin (A, C, W, B)

Dinotefuran (C, B)

Esfenvalerate (A, C, W, B)

Etofenprox (C, W, B)

Fenoxycarb (W)

Fipronil (A, C, W, B)

Imidacloprid (A, C, SW, W, B)

Malathion (A, C, SW-URBAN, GW, W, B)

Methoprene (W)

Permethrin (A, C, GW, W, B)

Prallethrin (A, C, W, B)

Propoxur (W, B)

Pyrethrins (C, W, B)

Pyriproxyfen (C, GW, W, B)

Spinosad (C, W, B)

Tetramethrin (W, B)

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Welcome back to Question of the Week!Question:Fleas are an epidemic in my town, and my dogs are covered in them! I...

Posted by Beyond Pesticides on Friday, August 21, 2015

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