How to Bug Proof Your Home from Head Lice

Pest Management In and Around Structures November 16, 2015 Print Friendly and PDF


Head Louse

There are three kinds of lice that infest humans: head lice, body lice and crab lice. They can be a great source of stress to the body. Children in particular suffer with head lice and become sleep deprived, which in turn lowers their immune system.

Lice can crawl relatively quickly; however, they cannot fly or jump and therefore direct contact with an infested object or person is required to contract them. Infestations of lice are called pediculosis, which is classed as a communicable disease.

The head louse and the body louse are closely related though their behavior is quite different. The head louse, as its name suggests, remains on the head of a person its entire life, the body louse spends most of its time in the seams of unwashed clothing and returns to the body only to feed. Crab lice are also known as pubic lice. They have legs adapted for grasping widely spaced hairs, such as those in the groin regions, though they can also spread to the armpits and facial hair (eyebrows, eyelashes and beard). All three lice require human blood and cannot live on birds or other animals. Lice feed by pressing their mouthparts against the skin of their hosts. Head lice are the most common louse problem in the United States. Easily spread by physical contact, infestations can occur under the best sanitary conditions. Every year, 6 to 10 million people in the United States contract head lice, three-quarters of which are school children less than 12 years old. Children are more likely to engage in close contact play, share head-gear, and are more opposed to washing their hair, so are more prone to infestations than adults.

Fortunately, head lice rarely transmit infectious diseases from person to person, and they are considered more of a nuisance than a health risk. However, the subsequent itching that accompanies an infestation can cause lack of sleep, and scratching can result in a secondary infection requiring antibiotic therapy. In extreme cases, the infested person may experience fatigue, chills, leg cramps and rashes. Intense itching on the back of the head or neck is an indication of an infestation. This occurs when the lice feed on the scalp. Examine individual hair shafts, concentrating in areas at the nape of the neck and behind the ears. Nits are most commonly found first, as they are much more numerous than mature lice. Look also for small, quickly crawling, and flat insects. Lice can be difficult to find, so examinations must be thorough. The best management technique is prevention.


  1. Launder clothing and bedding routinely including pets’ bedding with a hot wash and tumble dry.
  2. Regularly vacuum the home including all bedding and furniture upholstery.
  3. Do not buy secondhand beds, bedding or upholstered furniture.
  4. Do not share clothing or headgear and carefully inspect the clothing and baggage of travelers.
  5. Bathe yourself regularly and ensure other members of the household do also.
  6. Use of nit combs to remove eggs, insecticidal soaps and shampoos are the standard treatment methods.


What Are Head Lice and How Do They Spread?

Lice Eggs
Lice eggs are called nits, and typically hatch in 7-10 days. Nits are white-dark ovals (1.5 mm long), usually glued to hairs of the head near the scalp; if the eggs have yet to hatch, they are the same color as the persons hair. Nits are quite often found on hair around a person’s ears and back of the head. You cannot "catch” nits; the eggs must be laid on the hair by live head lice.
Nits Hatch Into Nymphs
Nits hatch into nymphs, immature forms which look like small adults. Both nymphs and adults have piercing-sucking mouthparts to pierce the skin for a blood meal. Within 24 hours of hatching, a nymph will take its first blood meal, and periodically thereafter as it grows into an adult (a period of 10-12 days).
Adult Head Lice
Adult head lice are approximately 2-3 mm length (about the size of a sesame seed) and range in color from white to brown to dark gray. They do not have wings or powerful jumping legs, so they move about by clinging on hairs with specially adapted claw-like legs. Adult head lice are swift-moving and tend to avoid light. Females may live up to 40 days, laying 6-7 nits per day, up to a total of 50-100 eggs during their lifetime!
People previously unexposed to head lice experience little irritation from their first bite. After additional bites, however, individuals may become sensitized and experience an allergic reaction; this includes reddening of the skin, itching, and overall inflammation. The reaction of individuals to louse bites can vary considerably!


Head Lice Facts:
  • Head lice do not prefer dirty hair.
  • Head lice are unable to survive away from a human host for more than about 48 hours (they cannot live in rugs, carpets, classrooms or school buses).
  • Head lice are not found on animals or household pets, and they are not transmitted from pets to humans.


Checking for Head Lice

A. Nit B. Not a Nit

Steps for Head Lice Checks:

  1. Shampoo hair first.
  2. Begin with good lighting for your inspection (a bright lamp or good natural light).
  3. Remove tangles with a comb or hairbrush.
  4. Divide the hair in sections and fasten the hair that is not being worked on.
  5. Use a hand lens or a magnifying glass to help detect nits and head lice.
  6. For nits, look near the scalp.

Eggs that are located more than one-cm away from the scalp are nearly always hatched and do not - by themselves - indicate an active infestation or need for treatment.

  1. If either adults or nits (less than a half inch from the scalp) are found, action will need to be taken.
  2. Everyone else in the household needs to be checked for head lice, including all adults.


Head Lice Fact:
  • During the early fall months (August to November) children should be inspected weekly.


Managing Nits and Adult Lice

Managing infestations of head lice requires four critical steps:

  1. The use of an effective head louse treatment.
  2. Head lice removal from the head by combing.
  3. Removal of head lice and nits from the household environment.
  4. Daily head checks and nit removal until all have gone, followed by weekly head checks to detect re-infestation.


Head Lice Management Fact:
  • Alternatives to insecticidal shampoos: soap shampoos that contain coconut or olive oils. Begin with four shampoo applications, each 3 days apart. Each successive shampooing kills newly-hatched nymphs.


  1. Insecticidal shampoos can be hazardous if not used properly; in all cases, follow label directions completely and carefully. Most over-the-counter products contain either pyrethrin or permethrin (NIX and Rid). We do not recommend the use of products containing lindane or malathion unless prescribed by a doctor. These products have been associated with a variety of adverse reactions. The person applying any shampoo treatment should wear rubber gloves, and body exposure should be minimized by confining the insecticide to the head hair. Never apply an insecticide to anyone who has open cuts, scratches, or inflammations, and never use these materials on infants without consulting a doctor. If head lice are persistent, you might try switching to a pyrethrin if you used permethrin the first time, or vice versa.
  2. Head lice combs (e.g. LiceMeister™ comb, or Robi Comb electronic comb), are needed for complete and effective louse removal; 20 to 30% of lice may still be alive after shampooing with pyrethrin or permethrin products. Head lice combs are effective in managing head lice infestations when used diligently every 2 days for up to two weeks. Note: using a head lice comb to remove the insects can take quite some time, but is completely safe.
  3. Remove tangles and divide hair into manageable portions.
  4. Use a head lice comb to comb hair from the scalp to the end of the hair.
  5. Dip the comb in a container of hot soapy water to drown head lice and remove nits after each combing.
  6. Look through each section of hair for remaining nits and head lice before moving on to the next section.
  7. Repeat all steps until all hair is systematically combed through.
  8. Clean nit removal comb with hot soapy water or soapy ammonia. An old tooth brush may help dislodge hair, nits, and head lice caught in the teeth of the comb.
  9. Hair drying with a hair dryer, and brushing hair will mechanically kill many lice!

What needs to be done in the home?
Once an infestation is detected, all clothes (including coats with hoods) should be washed in hot soapy water. Pillowcases, sheets, blankets and other bedding material should also be washed and placed in the clothes dryer on a "high heat" cycle to kill adult head lice and eggs. Non-washable items (such as headphones) should be dry cleaned or sealed in plastic bags and placed in the freezer at 50F or lower for 2 days or more. Vacuuming the home will remove hair with nits.

  • Continue weekly head checks of the whole family for at least a month.

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.