Identifying Fleas

There are over 1,000 types of fleas in the world. The most common flea you will encounter attacking people and a pet is the cat flea. This flea feeds on cats, dogs, and humans, as well as rodents, chickens, opossums, raccoons, and other animals. The dog flea (C. canis) and the human flea (Pulex irritans) are less commonly encountered.

WHAT DO THEY LOOK LIKE?

Adult fleas are about 1/16 to 1/8-inch long, dark reddish-brown, wingless, hard-bodied (difficult to crush between fingers), have three pairs of legs (strong legs that enable them to swiftly jump long distances), and are flattened vertically or side to side (bluegill or sunfish-like) allowing easy movement between the hair, fur or feathers of the host.

FLEA LIFE

Fleas go through three stages before they become adults (egg, larva, and pupa). It can take from 30 days to one year to complete this cycle. The immature stages are most commonly found in areas where the host animal rests and visits frequently. Although eggs are laid on the animal, they fall off and land on surfaces like carpets, furniture, pet bedding, etc. Larvae emerge from the eggs and feed on organic debris and adult flea feces in the carpet or other surfaces. The adult flea is the only stage routinely found on the animal. Adult fleas will live 7-10 days. The average female flea will lay 150 eggs in that time span.

Unlike many other flea species, adult cat fleas remain on their host. After mating and feeding, adult female fleas lay oval, white eggs. These smooth eggs easily fall from the host into cracks, crevices, carpet (the perfect flea environment!), bedding, or lawn covering. A mature female flea can lay up to 25 eggs per day for three weeks.

Small, worm-like larvae (1/16 to 3/16 inches long) hatch from the eggs within 48 hours. They are eyeless, legless, and sparsely covered with hairs. The larval body is translucent white with a dark colored gut that can be seen through their skin. They feed on adult flea feces, consisting of relatively undigested blood, which dries and falls from the host's fur. They will also eat dandruff, skin flakes, and grain particles. Larvae develop on the ground in areas protected from rainfall, irrigation, and sunlight, where the relative humidity is at least 70% and the temperature is 70o to-90oF. This stage lasts eight to 24 days, depending on the temperature and humidity.

These immature fleas will eventually spin silken cocoons in which they will develop (pupate) into adult fleas. Cocoons are sticky, attracting dirt and debris which will easily camouflage them. Under optimal conditions, new adults are ready to emerge from their pupal cocoons within two weeks. They can, however, remain in their cocoons up to 12 months in the absence of a host or unfavorable climatic conditions. Vibrations and/or elevated temperature stimulate adults to emerge. This ability of flea pupae to wait until a host arrives can result in a sudden increase of adult fleas when they emerge simultaneously from many accumulated flea pupae.

WHAT HAPPENS WHEN THEY BITE?

Adult fleas are not only a nuisance to humans and their pets, but can cause medical problems including flea allergy dermatitis (FAD), tapeworms, secondary skin irritations and, in extreme cases, anemia.

Although bites are rarely felt, it is the resulting irritation caused by the flea salivary secretions that varies among individuals. Some may witness a severe reaction (general rash or inflammation) resulting in secondary infections caused by scratching the irritated skin area. Others may show no reaction or irritation acquired after repeated bites over several weeks or months. Most bites usually found on the ankles and legs may cause pain lasting a few minutes, hours or days depending on one's sensitivity.

The typical reaction to the bite is the formation of a small, hard, red, slightly-raised (swollen) itching spot. There is a single puncture point in the center of each spot. (Ants and spiders leave two marks when they bite. Mosquitoes, bees, wasps and bedbugs cause a large swelling or welt). Also, fleas may transmit bubonic plague from rodent to rodent and from rodent to humans. Oriental rat fleas can transmit murine typhus (endemic typhus) fever among rats and from rats to humans. Tapeworms normally infest dogs and cats but may appear in children if parts of infested fleas are accidentally consumed.

Fleas are excellent jumpers, leaping vertically up to seven inches and horizontally thirteen inches. (An equivalent hop for a human would be 250 feet vertically and 450 feet horizontally.)

Fleas go through three stages before they become adults (egg, larva, and pupa). It can take from 30 days to one year to complete this cycle. The immature stages are most commonly found in areas where the host animal rests and visits frequently. Although eggs are laid on the animal, they fall off and land on surfaces like carpets, furniture, pet bedding, etc. Larvae emerge from the eggs and feed on organic debris and adult flea feces in the carpet or other surfaces. The adult flea is the only stage routinely found on the animal. Adult fleas will live 7-10 days. The average female flea will lay 150 eggs in that time span. Unlike many other flea species, adult cat fleas remain on their host. After mating and feeding, adult female fleas lay oval, white eggs. These smooth eggs easily fall from the host into cracks, crevices, carpet (the perfect flea environment!), bedding, or lawn covering. A mature female flea can lay up to 25 eggs per day for three weeks. Small, worm-like larvae (1/16 to 3/16 inches long) hatch from the eggs within 48 hours. They are eyeless, legless, and sparsely covered with hairs. The larval body is translucent white with a dark colored gut that can be seen through their skin. They feed on adult flea feces, consisting of relatively undigested blood, which dries and falls from the host's fur. They will also eat dandruff, skin flakes, and grain particles. Larvae develop on the ground in areas protected from rainfall, irrigation, and sunlight, where the relative humidity is at least 70% and the temperature is 70o to-90oF. This stage lasts eight to 24 days, depending on the temperature and humidity. These immature fleas will eventually spin silken cocoons in which they will develop (pupate) into adult fleas. Cocoons are sticky, attracting dirt and debris which will easily camouflage them. Under optimal conditions, new adults are ready to emerge from their pupal cocoons within two weeks. They can, however, remain in their cocoons up to 12 months in the absence of a host or unfavorable climatic conditions. Vibrations and/or elevated temperature stimulate adults to emerge. This ability of flea pupae to wait until a host arrives can result in a sudden increase of adult fleas when they emerge simultaneously from many accumulated flea pupae.

WHAT HAPPENS WHEN THEY BITE?

Adult fleas are not only a nuisance to humans and their pets, but can cause medical problems including flea allergy dermatitis (FAD), tapeworms, secondary skin irritations and, in extreme cases, anemia. Although bites are rarely felt, it is the resulting irritation caused by the flea salivary secretions that varies among individuals. Some may witness a severe reaction (general rash or inflammation) resulting in secondary infections caused by scratching the irritated skin area. Others may show no reaction or irritation acquired after repeated bites over several weeks or months. Most bites usually found on the ankles and legs may cause pain lasting a few minutes, hours or days depending on one's sensitivity. The typical reaction to the bite is the formation of a small, hard, red, slightly-raised (swollen) itching spot. There is a single puncture point in the center of each spot. (Ants and spiders leave two marks when they bite. Mosquitoes, bees, wasps and bedbugs cause a large swelling or welt). Also, fleas may transmit bubonic plague from rodent to rodent and from rodent to humans. Oriental rat fleas can transmit murine typhus (endemic typhus) fever among rats and from rats to humans. Tapeworms normally infest dogs and cats but may appear in children if parts of infested fleas are accidentally consumed. Fleas are excellent jumpers, leaping vertically up to seven inches and horizontally thirteen inches. (An equivalent hop for a human would be 250 feet vertically and 450 feet horizontally.)