Fleas
The Flea Life Cycle
Fleas reproduce much like butterflies do. Females lay eggs, which hatch into worm-like larvae. The larvae spin cocoons and become pupae. An adult flea emerges from the cocoon. In a population of fleas, about half are eggs, and about five percent are adults.
Female fleas can lay eggs only if they’ve had a meal. If a female emerges from her cocoon and isn’t able to find food, she’ll die without reproducing. But once she’s eaten, a flea can lay close to 20 eggs at a time, for a total of 500 eggs during her lifetime.
Most of the time, fleas lay their eggs on their host. The eggs are completely smooth, so they slide off of the host and land in its environment. In people’s homes, the eggs sink deep into carpet fibers and into floor cracks. Outside, flea eggs settle into the soil. Flea eggs are white — the black specks you see on flea-infested animals and their bedding are particles of dried blood and flea droppings.
In order to develop, flea eggs need a warm, moist environment: a temperature of about 70 degrees Fahrenheit (21 degrees Celsius) and 70 to 85 percent humidity. In these conditions, the eggs hatch in about 12 days. This 12-day window is one of the reasons why it can be hard to get rid of fleas. Some insecticides kill adult fleas but not eggs, which means a whole new set of fleas can emerge after the adults have died.
Flea larvae are about 1.5 millimeters long and look like white, segmented worms. They avoid light and migrate toward cracks in the floor, where they remain for their development. Unlike their parents, the larvae don’t eat blood. Instead, they eat skin cells, flea droppings and other debris. Larvae develop through three stages, molting after each.
After a week or two, flea larvae spin silk cocoons. They attach pieces of dirt and debris to their cocoons as camouflage. If food is plentiful, the adult flea emerges after about a week. Otherwise, the flea may stay in its cocoon for up to a year.
Most people think of fleas as a nuisance — they bite people and animals, causing itchy, red bumps. This reaction comes from substances in fleas’ saliva, and some people react to these substances more strongly than others. Often, fleas draw blood from two or three tightly spaced punctures, causing two or three itchy bumps.
Animals that develop a sensitivity to flea bites can scratch or groom themselves excessively. This can lead to rough skin, baldness and skin infections. Sometimes, these infections can be mistaken for a parasitic infection called mange. Itchy, uncomfortable pets can also be ill-tempered or restless.
In addition to being annoying, fleas can carry diseases. They can even transmit other parasites to people and animals. Flea larvae feed on the eggs of tapeworms. Once swallowed, the tapeworms begin to develop in the gut of the flea. If an animal swallows an infected flea while grooming, the animal becomes infected with tapeworm as well. The tapeworm grows in the intestine of the animal, shedding its egg sacs from the animal’s rectum as it sleeps. The sacs land in areas near the animal’s bedding — where flea larvae are likely to live — and the cycle begins again. People, especially children, can also become infected with tapeworms if they swallow fleas while petting animals or if people come into contact with infected waste and don’t wash their hands before eating.
It is important to not only treat your pets with a monthly flea preventative, but for extreme infestations of fleas, you may have to treat your house and yard as well. There are various sprays and powders you can purchase at most hardware stores. Vaccuuming is also very important on a regular basis in order to wake up any dormant larvae in order to kill them.
