Fleas are one of the more important groups of insect pests because they not only cause discomfort by biting, but they can transmit several diseases such as plague and murine typhus. Cat fleas are the most common domestic flea. In the United States, they are commonly found on both cats and dogs. Cat fleas are found throughout the United States and the rest of the world.
- Adults about 1/8" (2.5 mm) long
- Body laterally flattened (side to side); wingless
- Color brownish black to black, but reddish black when full of blood
- Female’s head twice as long as high
- Compound eyes well developed
- Both genal and pronotal combs present, each composed of 16 spines, and genal comb’s first 2 anterior spines of about equal length
- Femur of hind leg with 7-10 bristles on inner side
- Abdominal terga (dorsal plate of segments) 2-6 with a single row of bristles
- 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 twice the adult length (1/4"/3-5.2mm)
- Larvae whitish, slender, eyeless, and legless
- Well-developed head
- Anal struts/hooks 2, small
- Moderately long, backward-projecting hairs (setae) encircling each segment
- Last abdominal segment (10th) with 3 ventrolateral hairs (setae)
- European mouse flea (Leptopsylla segnis) has genal comb with only 4 spines.
- Rabbit flea (Cediopsylla simplex) with genal spines oriented vertically (vs. horizontal), comb spines with blunt/rounded ends.
- Dog flea (Ctenocephalides canis) with head length less than twice height, genal comb with spine I (anterior most) distinctly shorter than spine II (adjacent spine to posterior/ rear), hind leg femur with 10-13 bristles on inner side.
- Other fleas (various families) lack having both pronotal and genal combs or if both pronotal and genal combs present, then either have abdominal combs or have fewer than 16 spines in pronotal comb (dog flea with 16 pronotal spines, see above).
Females lay 4-8 eggs after each blood meal, laying some 400-500 during their lifetime. The eggs are smooth and not glued/stuck to the hairs or body but are deposited on or between hairs, or in the nest or bedding material. Hence, eggs deposited on the animal either fall or are shaken off, and are frequently found in cracks and crevices where pets sleep or frequent. Eggs are oval, whitish, and about 1/64" (0.5 mm) long. They usually hatch in about 2 days (range 1-12 days).
Flea larvae move about using the setal rings and abdominal struts/hooks. They have chewing mouthparts and feed on organic debris but almost all require dried fecal blood in order to complete development; they do not bite but feed on adult flea fecal blood. Larvae require high relative humidity (45-95%) and 1-2 weeks to several months to go through 3 instars. Last instar larvae then spin a cocoon and incorporate surrounding debris on its surface which provides camouflage. Under favorable conditions, the pupal stage may last 4-14 days or up to a year under harsh conditions. The pre-emerged adult remains in the cocoon for up to 20 weeks, where it is protected from adverse conditions, including pesticides. Adults are stimulated to emerge from the cocoon by mechanical depression of the cocoon, an increase in temperature, and possibly vibrations. Larvae and pupae are typically found where the animal sleeps or frequents.
Adults usually begin to seek a blood meal on the second day after emergence, but can live for several months on their stored body fat. Adults, unlike many other fleas, once on a host tend to spend all of their time on the host, feeding, mating, and laying eggs, unless dislodged. Although they have a preferred host, they will readily bite and can survive using other species as hosts. Depending on conditions, adults usually live only several days because normal cat grooming removes up to 50% of the fleas; otherwise, they can survive about a year.
Cat fleas may transmit plague. There is very strong circumstantial evidence that they may transmit murine typhus. Cat fleas serve as intermediate hosts of the dog tapeworm, Dipylidium canninum (Linnaeus), and the rodent tapeworm, Hymenolepis diminuta (Rudolphi). These tapeworms occasionally infest humans, especially very young children. The dog tapeworm commonly infests cats that spend time outdoors.
It is not necessary to have pets in the building in order to have fleas present. Since fleas can jump about 6" (15 cm) vertically, they can easily hitch a ride on shoes, trousers, etc.
Many vacationers who may have been unaware of the few adult fleas present, are often greeted and severely attacked by fleas upon their return. This can occur even if the building has been vacant of animals and people for as long as 6 months or so. This situation can occur because of the potentially long pupal period, adults can live for months without food, and because fleas have not been removed via normal vacuuming. Also, fleas are normally removed from the interior environment by taking up residence on the pet(s).
Fleas are typically found where animals sleep or frequent, including along their usual avenue of travel, because this is where eggs and adult fecal blood accumulate. Most larvae will be found in similar places but especially in areas with high moisture which is necessary for their survival. Pupae will be found in the same situations as larvae. Such places include both indoor and outdoor situations. Cat fleas are also found on other urban hosts such as opossum, fox, mongoose, and occasionally rats.
Flea larvae die at relative humidities below 45% and above 95%, and hence, are rarely found outdoors in arid climates. Larvae fail to develop at temperatures below 55°F (13°C) and at or above 95°F (35°C).