Cat fleas, Ctenocephalides felis, are the most common ectoparasite on domestic cats and dogs (Figure 1). Dog fleas, C. canis,look like cat fleas but are rare in California. Sticktight fleas, Echidnophaga gallinacea, are commonly found on ground squirrels and poultry; the females firmly attach themselves along the ears and eyes of their host (Figure 2). They can become a problem with pets that roam. The ground squirrel flea, Oropsylla montana, is found on ground squirrels and is the vector of sylvatic plague in California. However, fleas on cats or dogs in California most likely are cat fleas.
Adult fleas are no larger than 1/8 inch long, so it is difficult to see a number of the characteristics used to describe them. These reddish-brown, wingless insects are laterally compressed, so they look as if they are walking on edge. Cat fleas have both pronotal and genal combs. They have piercing-sucking mouthparts through which they obtain blood meals from their hosts.
Unlike most fleas, adult cat fleas remain on the host where feeding, mating, and egg laying occur. Females lay about 20 to 50 eggs per day. Cat flea eggs are pearly white, oval, and about 1/32 inch long (Figure 3). The eggs are smooth and readily fall from the pet and land on surfaces such as bedding and carpeting in the animal’s environment. They hatch in about 2 to 5 days.
Flea larvae are no larger than 3/16 inch long, hairy, and wormlike with a distinct, brownish head but no eyes or legs (Figure 4). The larvae feed on dried blood and excrement adult fleas produce while feeding on the pet. Larval development is restricted to protected places where there is at least 75% relative humidity. The larvae feed and crawl around for 8 to 15 days before building small, silken cocoons in which they pupate and develop into adults. Debris, such as pet hair or skin or carpet fibers, usually covers the pupae, providing visual camouflage.
Flea larvae develop more quickly at higher temperatures, preferring areas that are 70° to 90°F. At cool temperatures, fully formed fleas can remain in their cocoons for up to 12 months. Warm temperatures and mechanical pressure caused by walking on or vacuuming carpet stimulate emergence from the cocoon. At normal room temperatures, the entire life cycle can occur in about 18 days.
An adult cat flea generally lives about 30 to 40 days on the host. When normal grooming activity is restricted, 85% of adult females survived for 50 days. You can find fleas on pets throughout the year, but numbers tend to increase dramatically during spring and early summer when conditions favor larval development.
Recent advances in molecular research indicate cat fleas are capable of transmitting a murinelike typhus disease in humans, cat flea rickettsiosis. The symptoms are similar to murine typhus but less severe, including headaches, chills, fever, vomiting, and rash. This rickettsial agent is widely found in cats and cat fleas worldwide. It is likely that many previously diagnosed cases of murine typhus actually might have been cat flea rickettsiosis.
Fleabites consist of a small, central, red spot surrounded by a red halo, usually without excessive swelling. They usually cause minor itching but can become increasingly irritating to people with sensitive or reactive skin. Some people and pets suffer from fleabite allergic dermatitis, characterized by intense itching, hair loss, reddening of the skin, and secondary infection. Just one bite can initiate an allergic reaction, and itching can persist up to 5 days after the bite.
Cat fleas serve as intermediary hosts of dog and cat tapeworms. Cats or dogs can acquire this intestinal parasite while grooming themselves if they ingest adult fleas that contain a cyst of the tapeworm. Children occasionally can acquire these tapeworms too.
New, safer, and more effective products aimed at controlling adult fleas on pets have made cat flea management without pesticide sprays, shampoos, and dusts feasible in most situations. Management of fleas on pets must occur in conjunction with regular, thorough cleaning of pet resting areas indoors and out. Once fleas infest a home, control will require a vigilant program that includes vacuuming, eliminating fleas on pets, and cleaning up and possibly treating shaded outdoor locations where pets rest.
On the Pet
Several types of products are available to control fleas on dogs and cats. The newer products are either applied topically to the body of the pet or provided orally (Table 1). Products containing fipronil, permethrin, or amitraz also are designed to control ticks. Products containing the insect growth regulators (IGRs) methoprene and pyriproxyfen are designed to provide long-term control of flea eggs and immatures in the environment.
If you administer oral or topical products early in the year before flea populations begin to build, the products can prevent fleas from establishing themselves in your home. Contact your veterinarian for advice in selecting the best flea-control product for your situation. Supplement the use of these products with good housekeeping in areas where the pet rests.
Indoors. Controlling cat fleas in buildings requires a variety of approaches. Before starting a control program, look through each room to determine areas where larval development occurs. Flea populations are highest in places where dogs or cats regularly sleep. You usually won’t find flea larvae 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.
Sanitation. Thoroughly and regularly clean areas where you find adult fleas, flea larvae, and flea eggs. Vacuum floors, rugs, carpets, upholstered furniture, and crevices around baseboards and cabinets daily or every other day to remove flea eggs, larvae, and adults. Vacuuming is very effective in killing larvae in the carpet, picking up adults, and stimulating preemerged adults to leave their cocoons. Recent studies suggest that destroying the vacuum bags isn’t necessary. Launder pet bedding in hot, soapy water at least once a week. Thoroughly clean items you bring into the building, such as used carpets or upholstered furniture, to prevent these from being a source of flea infestation.
Insecticides. Several insecticides are registered for controlling fleas indoors. The most effective products also contain the IGR methoprene or pyriproxyfen. Use a hand sprayer or aerosol to apply insecticides directly to infested areas of carpets and furniture. Total release aerosols, or room foggers, don’t provide the coverage and long-term effectiveness of direct sprays unless they contain methoprene or pyriproxyfen. 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.
Spray carpets, pet sleeping areas, carpeted areas beneath furniture, baseboards, windowsills, and other areas harboring adults or larvae. Fleas will continue to emerge for about 2 weeks after treatment, because the spray doesn’t kill pupae. Continue to vacuum, and don’t treat again for at least several weeks.
Outdoors. In California, outdoor flea populations are most prevalent in coastal localities and other places with moderate daytime temperatures and fairly high humidity levels. In Central Valley locations, populations can become very numerous in shaded and protected areas such as sheltered animal enclosures, crawl spaces under buildings where feral animals might sleep, and vegetated areas adjacent to buildings. Infested outdoor locations left untreated can lead to fleas reinfesting your pets. However, treating the pet with any of the preferred pet treatment products listed above normally will prevent re-infestation.
Outdoor sprays aren’t necessary unless you detect significant numbers of adult fleas. One way to do this is to walk around pet resting areas wearing white socks pulled up to the knee. If fleas are present, they will jump onto socks and be readily visible.
Products for eliminating adult fleas outdoors are somewhat limited because many field populations of cat fleas are resistant to pyrethroids such as permethrin. Apply sprays directly in locations where pets rest and sleep such as doghouse and kennel areas, beneath decks, and next to the foundation. It is seldom necessary to treat the entire yard or lawn areas. Flea larvae are unlikely to survive in areas with exposure to sunlight or substantial foot traffic.
HANDLING A FLEA EMERGENCY
If your home is heavily infested with fleas, take these steps to get the situation under control.
Inside the Home
1. Locate heavily infested areas, and concentrate efforts on these areas.
2. Wash throw rugs and the pet’s bedding.
3. Vacuum upholstered furniture. Remove and vacuum beneath cushions and in cracks and crevices.
4. Vacuum carpets, especially beneath furniture and in areas that pest frequent. Use a hand sprayer to treat all carpets with an insecticide that contains an insect growth regulator.
5. Allow carpets to dry, then vacuum a second time to remove additional fleas the spray caused to emerge.
6. Continue to vacuum for 10 days to 2 weeks to kill adult fleas that continue to emerge from pupal cocoons.
On the Pet
Use a spot-on or a systemic oral treatment, which you can purchase from veterinarians or online.
Outside the Home
If you treat your pets with spot-on or oral treatments, you‘ll rarely need to spray outdoors.