Pests in Gardens and Landscapes: Quick Tips

Head Lice

Published   1/04

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Life cycle of head lice.

Life cycle of head lice: adult, egg laid on hair, and nymph.

Head lice can be removed with special metal combs.

Head lice can be removed with special metal combs. Pin up hair after it has been combed.

Head lice can infest anybody, but children are prone to infestations because they play closely and share items that come in contact with the head like hats, headphones, and combs. Head lice are not known to transmit any infectious diseases; they are more of a nuisance than a health risk. Children with head lice, however, are generally not allowed to attend school as long as nits are found in their hair.

Head lice facts:

  • Head lice cannot hop, fly, or jump; they crawl. Lice spread only through direct contact with an infested object or person.
  • Head lice spend their entire life in head hair and can only survive off a human head for about 1 or 2 days.
  • A newly hatched louse must ingest blood within minutes of birth to survive.
  • Head lice cannot live on family pets
  • Nits (eggs) that are more than 1/4 inch from the scalp probably are dead or have already hatched.

What to look for:

  • Intense scratching on the back of the head or neck.
  • Tiny, white eggs (nits) glued to the hair near the scalp.
  • Small, rapidly crawling flat insects.

Four steps necessary to manage an infestation of head lice:

  • Use a head louse shampoo if you observe active lice or viable eggs.
    • Avoid shampoo products containing lindane, which are available by prescription only. Pyrethrin and permethrin are safer, more effective, and less polluting to wastewater than lindane. Not all eggs will be killed.
    • To avoid insecticides entirely, use soap shampoos that contain coconut or olive oils. Most soap shampoos kill all stages of the louse except the egg. Because they are not as effective as products containing pesticides, you must be sure to comb and repeat these shampoos four times at 3-day intervals. Successive shampooing kills newly hatched lice.
  • Remove nits from the head by combing with a specially designed nit comb.
    • This step is the key to successful control. Repeat daily as long as you find live lice or nits within 1/4 inch of the scalp. Use a metal comb specially designed for removing head lice and their eggs. Combs sold with head lice shampoos are not generally effective. Infested hair can also be cut out with small safety scissors.
  • Remove lice and nits from the household.
    • Wash clothing and bedding of the infested person in hot water (at least 140°F) and dry in a hot dryer or have them dry cleaned. Place other items (earphones, bike helmets) in plastic and put in a freezer that is 5°F or lower for at least 10 hours. Clean any object that might have come in contact with the infested person’s head (stuffed animals, car seats). Vacuum carpets and upholstery. Pesticide sprays are not recommended.
  • Check heads and remove nits daily until infestation is gone. Follow with weekly head checks to detect reinfestation.

Read more about Head Lice.

Minimize the use of pesticides that pollute our waterways. Use nonchemical alternatives or less toxic pesticide products whenever possible. Read product labels carefully and follow instructions on proper use, storage, and disposal.

Statewide IPM Program, Agriculture and Natural Resources, University of California
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