Human Head Lice

Facts, Identification & Control


Pediculus humanus capitis


Head lice are blood-sucking insects that live in human hair. Primarily found on the scalp, these wingless, six-legged pests do not live on pets. Lice appear in three life stages – eggs (nits), nymphs (juvenile adults) and adults. After hatching, lice go through the nymph stage where they molt three times before reaching adulthood.

Louse eggs measure about 1/16 of an inch and look translucent, white, or yellow-brown. Nymphs are about 1/16-1/8 inch long, are grey or tan colored and look like a smaller version of an adult louse. Adults are about 1/8 inch long, about the size of a sesame seed and grey or tan colored. An easy way to identify head lice eggs is to look for them glued to the hair shafts near the scalp. Head lice are flat and their legs have a claw that enables them to grasp hair shafts as they feed using their piercing-sucking mouthparts.


Head lice are parasitic on humans since they take blood meals by puncturing the skin and sucking blood several times a day. Head lice live on the skin among the hairs on the head and if someone is heavily infested, lice may be found in the eyebrows and eyelashes. Lice attach eggs to hair shafts with a glue-like substance. Should a nymph or adult head louse become dislodged from their human host, they survive for only 1-2 days since they are dependent upon the host for blood meals, moisture and suitable warmth. While eggs may survive for up to three days off the human host, they do not hatch at temperatures lower than those near the scalp. Nits hatch about 5-10 days after being laid.

Head lice can be transmitted from one host to another and do so via close contact such as head to head touching with an infected person. Also, head lice may be transmitted from one person to another from shared articles such as combs, hairbrushes, caps, headscarves or bed clothing. However, spread by such inanimate objects are much less frequent than spread by person-to-person contact. Pets are not capable of spreading head lice to humans.


Adult female head lice normally produce 5-6 eggs per day for about 30 days.


The presence of adult or juvenile head lice, eggs on hair shafts, itching and sores caused by scratching of the scalp are signs of a head lice infestation.


Head lice are found throughout the United States.


Your pest management professional can provide important information and recommendations for head lice management; however, it is best to contact your family physician or another health professional should head lice become a problem.

Head lice are not a condition that indicates poor sanitation or poverty since they can affect anyone. Although they are not transmitters of disease, they can cause extreme irritation, social stigma and may also contribute to secondary bacterial infections that result from itching and sores in the scalp area.

Lice can be removed manually with specially designed combs and can be treated with over-the counter or prescribed medications. Also laundering of all bedding and clothing using hot water and the hot setting on a clothes dryer will help reduce the chances of spreading head lice.

Head Lice & Dogs
Unlike fleas that affect canines, cats, rodents etc., human head lice cannot survive without a viable host on which to feed. Human head lice are endemic to humans and will not affect dogs, though other species of lice have been known to bite dogs.

Lice vs Fleas
However, a flea infestation can be confused for a lice infestation. Fleas are pests which do affect dogs, and they infest homes and yards quickly. They may live within the carpet of a home for months before emerging as pests. Fleas, like lice, can bite humans as well.

If your pet shows signs of excessive itching or restlessness, he or she may be harboring fleas. Be sure to clean all bedding and check for signs of flea infestations around your home. Should a flea infestation become evident, contact your pest control professional and veterinarian for treatment options.

Can Head Lice Carry Diseases?
Head lice are not known to transmit any diseases and are not considered a health hazard. Head lice infestations may show no symptoms except for the presence of the lice when the infestation is small in number or it is a person’s first time to experience a head louse infestation. Itching is the most common reaction to head lice and is caused by an allergic reaction to louse bites. Other symptoms may include a tickling sensation, irritability, sleeplessness and sores on the head caused by scratching. Secondary infection may result if sores become infected.