The presence of “bugs” in hair is a common concern. Only a few specific organisms are adapted to live on human hair and scalp. This article clarifies what creatures can truly live in human hair and how to manage them.
The Common Culprit: Head Lice
Head lice, Pediculus humanus capitis, are tiny, wingless insects that live among human hairs and feed on blood from the scalp. An adult louse is tan or grayish-white, about the size of a sesame seed, with six hook-like legs for clinging to hair. They move by crawling and cannot jump, hop, or fly.
The life cycle of head lice involves three stages: eggs (nits), nymphs, and adults. Female lice lay small, oval nits, firmly attaching them to the base of hair shafts, usually within 1/4 inch of the scalp. Nits hatch into nymphs in 7 to 12 days, and nymphs mature into adult lice in 7 to 12 days.
Common signs of a head lice infestation include itching, an allergic reaction to their bites that may not appear for weeks. Some people might also feel a sensation of movement in their hair or develop small red bumps from scratching. Head lice are not dangerous and do not transmit diseases. They are human parasites and cannot live on or be spread by pets.
Other Parasites: Clarifying Their Habitats
Beyond head lice, other parasites can affect humans but do not reside in head hair. Body lice (Pediculus humanus humanus) primarily live in clothing and bedding seams, only moving onto the skin to feed. They do not inhabit the hair itself.
Pubic lice (Pthirus pubis), often called “crabs,” prefer coarse body hair, such as that found in the pubic area, but can also infest eyelashes, eyebrows, beards, or armpit hair. Their flattened, crab-like bodies are adapted for grasping thicker hair shafts, making head hair an unsuitable habitat. Mites like Sarcoptes scabiei, which cause scabies, burrow into the skin to lay eggs, rather than living on the hair or scalp surface. Microscopic Demodex mites are common inhabitants of hair follicles and oil glands on the face, but they are not visible to the naked eye and do not cause the typical “bug in hair” sensation.
How Infestations Occur and What Not To Believe
Head lice infestations occur through direct head-to-head contact with an infested person, particularly among children during play, slumber parties, or sports activities. Lice crawl from one head to another. This direct contact is the primary mode of transmission.
A common misconception is that head lice indicate poor hygiene. Lice can infest anyone, regardless of how often hair is washed, and they prefer clean hair for better egg attachment. While less common than direct contact, sharing personal items like hats, scarves, combs, brushes, or headphones can potentially spread lice. The risk is lower as lice do not survive long off a human host; adult lice die within one to two days if they fall off a person and cannot feed.
Strategies for Management and Prevention
Effective management of head lice involves several steps. Over-the-counter medicated shampoos or lotions containing ingredients like permethrin or pyrethrin can kill lice and some eggs. Prescription medications are also available if initial treatments are ineffective. Wet combing, using a fine-toothed comb on wet hair saturated with conditioner, is another effective method to physically remove lice and nits. This process should be repeated regularly to ensure all newly hatched lice are removed before they can lay eggs.
Cleaning the home environment is less critical than treating the infested individual. Washing bedding, clothing, and other items that contacted the infested person in hot water (at least 130°F) and drying them on high heat can help. Items that cannot be washed can be sealed in a plastic bag for two weeks. Vacuuming floors and furniture where the infested person sat is also recommended.
Prevention focuses on avoiding head-to-head contact and discouraging the sharing of personal items that touch the head. Regular checks of children’s hair can help in early detection and treatment.