Pest and Diseases Image Library, Bugwood.org

Fleas are public health pests that diet on blood from dogs, cats, livestock and other warm-blooded animals. If their primary host is unavailable, they can feast on human blood. Due to their small size (1/16 to 1/8 inch long) and jumping ability, people can mistake fleas for springtails. Thus, proper identification is a must before treatment. Fleas like to bite humans around ankles and waists, giving them itchy, red marks surrounded by reddish halos. At any given time, a flea population consists of only 1 percent adults, 14 percent pupae, 35 percent larvae and 50 percent eggs. A female flea lays eggs within 24 to 48 hours of latching on a host. On average, the female lays 40 to 50 eggs a day (two eggs/hour).

Fleas have a flattened body side to side, which helps them move easily through hair. Once attached to the host, fleas do not intend to leave, focusing on feeding, mating and laying eggs. Fleas’ eggs roll off into wherever the host goes and hatch into larvae in three to five days. In order to develop, larvae need adults’ feces as food, protection from direct sunlight, temperatures from 45°F to 90°F, and 50 to 85 percent relative humidity (RH).

CONTROL EFFORTS. In order to remove fleas from a structure, use a proper hand-held sprayer with a mixture of a proven residual insecticide and an insect growth regulator (IGR). It is recommended that these pesticides are in the emulsifiable concentration (EC) formulation to easily penetrate carpets and other surfaces where fleas hide. To control the source of flea infestations, pets inhabiting the treated premises must be inspected and properly treated with approved flea control products registered for animal applications. These products should be used by a veterinarian or the owner.

Thoroughness is a must for successful flea elimination. Treat all areas where pets and other animals are known to frequent, as well as in common flea harborage places and where previous infestations have been known to occur. Remember to treat dark and warm places, under cushions of sofas and upholstered furniture, in carpet fibers and corners, along carpet edges and baseboards, cracks between tile and wood floor, under refrigerators, and under and around pet sleeping and resting places. Approved ready-to-use (RTU) aerosols can also be used to control fleas. These products contain ingredients to destroy the adults as well as an IGR to manage the larvae. Since biting adults represent only a minor fraction of the total flea population in any infested area, including an IGR in the tank mixtures is a must to disrupting flea development from larvae to adults.

Fleas can thrive outdoors in various moist, shady habitats. These sites work as permanent sources for flea infestations. In order to manage outdoor flea populations, use a power mister with a mixture of approved residual pesticide and adjuvant (spreader-sticker) to treat all flea hiding and entry areas. Pay particular attention to areas around the exterior of the structure, under porches and decks, as applicable, within a garage, around tall grasses and weeds, under shrubs where pets rest and lounge, around doghouses, and around shady and moist places.

Set realistic expectations about the treatments to reduce the number of callbacks. Let customers know that fleas may continue to be noticed, as adults will keep emerging from their cocoons for two weeks after the treatment. This period is known as the “pupal window.” The emerging fleas will die soon from the residual effects of the insecticide. A follow-up treatment is only recommended if fleas are seen three to four weeks after treatment. Recommend to the customer that carpets and furniture should be vacuumed thoroughly and regularly after treatments (vacuum cleaner bags should be discarded in an outdoor trash container). Washing treated areas, or shampooing the carpet after treatment IS NOT a good idea. These practices will diminish the residual effects of the insecticides being used.

The author is technical and training director at Adam’s Pest Control, Medina, Minn.