The Human Flea

Common Name:
Human Flea
Scientific Name:
Pulex irritans (Linnaeus)


This common name results from their frequent occurrence on humans under poor sanitary conditions, but they also infest pets and domestic animals. They can be vectors of plague and murine typhus, and serve as intermediate hosts of the dog tapeworm. Human fleas are found throughout the warmer parts of the world, and in the United States, especially on the Pacific Coast, the midwest, and in the south.


Adults about 1/8" (2.5-3 mm) long. Body laterally flattened (side to side); wingless. Color reddish brown. Head with front rounded, ocular bristle inserted below eye; genal combs lacking. Pronotal comb lacking; mesopleuron (side of mesothorax) not divided by a vertical thickening; thorax not reduced, dorsum (top) equal to or longer than lst abdominal segment. Abdominal terga (dorsal plates) 2-6 with a single row of bristles. In addition, antennae short, 3-segmented; ocelli lacking; legs long, coxae large, tarsi 5-segmented; usually jumping insects; mouthparts piercing-sucking with well-developed palps. Mature larvae about 1/4" (4.6-6 mm) long. Larvae whitish, slender, eyeless, and legless. With a well-developed head. Anal struts/hooks 2, small. With moderately long, backward-projecting hairs (setae) encircling each segment. Last abdominal segment (10th) with 4-6 (usually 5) ventrolateral hairs (setae).


  1. Pulex simulans with male's dorsal aedeagal scierite broad and blunt, crochet flattened (vs dorsal aedeagal scierite long and narrow, crochet triangular.

  2. Oriental rat flea (Xenopsylla cheopis) with mesopleuron (side of mesothorax) divided by a vertical thickening, and ocular bristle inserted in front of eye.

  3. Sticktight flea (Echicnophaga gallinacea) and Chigao flea (Tunga pentrans) with front of head angular, dorsum (top) of thorax shorter than lst abdominal segment dorsum; in addition, sticktight flea with a group of spinuies (short spines) on inner side of hind coxae.

  4. Polygenis gwyni (family Rhopalopsyllidae) with 2 rows of bristles on typical abdominal segment.


Females lay 4-8 eggs after each blood meal, for a total of up to 400 in a lifetime. Eggs usually fall off the host and hatch in 2-14 days. Larvae usually feed on organic matter such as droppings from adult fleas and feces of animals, but can feed satisfactorily on crushed rat faces alone. The larvae go through 3 instars in 1-5 weeks and then spin a cocoon and pupate. Under favorable conditions, adults emerge in 1-3 weeks. Developmental time (egg to adult) may be as short as 17 days. Adults may live more than 2 years.


Besides humans, these fleas infest cats, dogs, and other domestic animals, especially pigs. Most problems with human fleas occur in rural or farm areas. Infestations start with the farm animals and are then brought into the home. The human flea attacks a wide variety of wild animals including coyotes (Canis latrans Say), prairie dogs (Cynomys spp.), badgers, mice, ground squirrels (Spermophilus spp.), skunks (Mephitis spp.), fox, deer (Odocoileus spp.), opossums, and burrowing owls (Speotyto cunicularia (Molina)). In a Florida study, 20% of the flea-infested dogs had the human flea on them accounting for about 7.5% of the fleas present. In Florida, human fleas are more prevalent in the cooler months on dogs kept outside. Bites of human fleas may be generally distributed over the human body whereas, cat flea bites which tend to be concentrated on the lower legs. Human fleas can vector plague. On the Pacific Coast, human fleas are often responsible for a dermatitis or allergy due to flea bites.