head lice


Head Lice (Pediculus humanus capitis)

Head lice are external parasites (blood feeders) of people, particularly children of school age. Lice glue their eggs (nits) to hairs, which can only be removed with a thorough combing with a fine-toothed “nit” comb. Adult lice live about a month and spend their entire life cycle on the host. If separated from the host, lice do not live longer than 48 hours, therefore, it serves no purpose to treat schools to control lice. Females lay 50 to 100 eggs, which hatch in 5 to 14 days. It is very important to realize that only 90% of the eggs hatch after 9 days. The life cycle, egg to sexually mature adult, normally requires about three weeks to complete. Lice are spread from person to person mainly through physical contact, sharing clothing (especially hats) and beds.

Control of lice is achieved only through the diligent and persistent insecticidal shampoos and creams, baby or mineral oil, nit combs, short hairstyles, and by avoiding infested persons. Daily laundering of clothes and bedding for the first few days after the initial treatment will eliminate lice that have fallen off their host and prevent them from re-infesting family members.

An effective non-chemical method of controlling lice is baby oil or mineral oil. Simply saturate the hair with the oil at night, wrap the head with a towel to avoid staining sheets and pillowcases, then in the morning, and shampoo the hair to remove the oil. The oil must remain on the head for at least 8 hours to be effective. Even though it is very likely that a single application of the oil will kill all stages (eggs, nymphs and adults) of the lice, I recommend retreatment about 7 days after the initial treatment. I believe that a second and third treatment is necessary to insure control of lice. There is a huge difference between killing every egg and killing just some of them. All it takes is a few eggs to survive and the lice will reappear, over and over again, in a few weeks time. Also, it is very important to treat every member of the family and an earnest attempt should be made to have other families, whose children play with yours, treat their children as well. I have used NIX (Permethrin) and baby oil when my children have had lice. I treated them, as well as everybody else in the family, with NIX. Treatments of baby oil were repeated every week thereafter for three consecutive weeks. This eventually got rid of the lice.

Be sure to read and follow all instructions and safety precautions found on the label before using any pesticide.

Head Lice And Eggs-236x300
Head Lice (Pediculus humanus capitis) and eggs
Comb for removing lice eggs from hair shafts
Comb for removing lice eggs from hair shafts
Head lice nitts on human scalp
Head lice nitts on human scalp

Accessibility Questions:

For questions about accessibility and/or if you need additional accommodations for a specific document, please send an email to ANR Communications & Marketing at anrcommunications@anr.msu.edu.