Flea problems tend to peak at the end of summer. Dealing with an infestation requires a significant amount of time, patience, and effort, as well as an approach that includes consideration of both the pet and its environment. Only an estimated 5% of the fleas in an infestation on animals are adults (Figure 1). About 50% are in the egg stage, 35% are larvae (Figure 2), and about 10% are pupae. Persistence and patience are essential. Concentrating solely on control of adults without addressing immature stages in bedding, carpets, and stuffed furniture will keep flea control from being successful.

Figure 1. Adult flea. (Photo: Lee Townsend, UK)

Figure 1. Adult flea. (Photo: Lee Townsend, UK)

Figure 2. Flea larvae do not have legs, but strong bristles allow them to move. The dark digestive tract contains dried blood and feces from adult fleas.(Photo: Lee Townsend, UK)

Figure 2. Flea larvae do not have legs, but strong bristles allow them to move. The dark digestive tract contains dried blood and feces from adult fleas.(Photo: Lee Townsend, UK)

Management Options

Treat the animal to kill adult fleas

The newest flea control products often are available only through veterinarians, but many can be obtained at pet supply stores or purchased on-line. Pet owners should visit with their veterinarian before using products to make sure that they are compatible with other treatments the pet may be receiving. Here are some examples.

Brand name Active ingredients Pet Form Targets
Program Program Plus lufenuron + milbemycin oxime Dogs Tablet Adult fleas, heartworms & other nematodes
Advantage 9.1% imidacloprid Dogs & Cats Topical Adult fleas
Advantage Multi imidacloprid + moxidectin Dogs & Cats Topical Adult fleas & nematodes
Advantix 8.8% imidacloprid & 44% permethrin Dogs Topical Adult fleas & ticks
Frontline Top Spot 9.7% fipronil Dogs Topical Adult fleas & ticks
Frontline Plus 9.8% fipronil & 11.8% methoprene Dogs & Cats Topical Adult fleas, larval fleas, ticks
Revolution selamectin Dogs Topical Adult fleas, larval fleas, nematodes
Zodiac Spot On Plus for Cats 3.6% methoprene + 40% etofenprox Cats Topical Adult & larval fleas and ticks
ProMeris for Dogs 14.3% metaflumizone + 14.3% amitraz Dogs Topical Adult fleas, ticks, demodectic mange mites
Zodiac Spot on Flea Control 45% permethrin Dogs Topical Adult fleas & ticks
Comfortis spinosad Dogs Tablet Adult fleas

Many flea control products are designed to be used in a preventive program before pets are infested. Specific formulations of the same active ingredient may be separated for dogs or cats, and may also be available for specific weight classes to ensure a safe but adequate dose. If a quick knockdown is needed, check the product label and other information to see how quickly you can expect results; some are much quicker than others. Flea shampoos or dusts are inexpensive but may not provide the lasting protection of a topical treatment.

Control immature stages of the flea

Failure to control immature stages is one of the most common reasons for control failures. Female fleas lay their eggs on the animal, but the eggs do not stick to the pet; instead, they fall off, usually onto the surfaces where the animal sleeps or regularly lays. There the worm-like flea larvae develop, feeding on dried blood and feces. Mature larvae spin a loose silk cocoon and pupate. Ultimately, adult fleas emerge to repeat the cycle. Eggs, larvae, and pupae account for an estimated 95% of the total flea population. Unless these areas are cleaned and treated, the infestation will persist.

Look through each room to identify potential “hot spots.” Here are some important steps to take:

  • Wash or clean throw rugs and pet bedding in hot water to kill flea eggs, larvae, and pupae. If animals sleep with family members, all bedding must be washed.
  • Steam clean or vacuum carpets thoroughly everywhere the infested pet is allowed to roam. Flea larvae are not usually found in areas of heavy pedestrian traffic or locations that receive exposure to sunlight; they are likely to be present in areas where adult fleas have left dried blood and feces.
  • Treat areas where pets spend time (other than family beds) with an insect growth regulator (IGR). Methoprene is the most common one. Focus on locations where pets go in and out of the house; sleep and rest; jump off beds, sofas and chairs; and other places where they spend time with family members.
  • Vacuum carpets, especially beneath furniture and in areas frequented by pets. Use a hand sprayer to treat all carpets with an insecticide that contains an insect growth regulator. Allow carpet to dry and vacuum a second time to remove additional fleas that were induced to emerge. Continue to vacuum for 10 days to 2 weeks to kill adult fleas that continue to emerge from pupal cocoons. Vacuuming is very effective in picking up adults and stimulating adults to leave their pupal cocoons. Flea eggs, larvae, and pupae can survive and develop inside vacuum bags and adults may be able to escape; immediately seal the used vacuum bag in a plastic trash bag and place it in a covered trash container.
  • Launder pet bedding in hot, soapy water at least once a week.

If fleas are still around after treatments

  • The pupal stage of a flea takes place in a loosely woven silk cocoon. This stage is not affected by any insecticide or IGR applications so adults must emerge to be killed.

Notes re: insecticides

Total release aerosols (“room foggers”) do not provide the coverage and long-term effectiveness of direct sprays unless the fogger contains an insect growth regulator. Treatments with insecticides other than IGRs often fail to control flea larvae because the treatment material fails to contact them at the base of carpet fibers where they develop.  Here are some example products that can be used:

  • Zodiac FleaTrol Carpet & Upholstery Pump Spray 0.01% methoprene + 0.28% permethrin
  • Zodiac Carpet & Upholstery Powder 2.5% linalool, 0.075% pyrethrins, 0.02% nylar


By Lee Townsend, Extension Entomologist



Posted in Pet Pests