-- Nit-picking is the key to control of a head
lice infestation --
Summary: "Nit" is another name for lice eggs and the term nit picking means removing nits from hair usually by combing with a metal nit comb or crushing nits between finger nails. Head lice (Pediculus capitis) and pubic lice (Pthirus pubis) attach their eggs directly to body hairs close to the skin surface. The physical removal of these nits ("nit picking), is the single most important part of any effective head lice treatment.
The term "nit" is just another name for egg. Head lice and pubic lice attach there nits, or eggs, to head or body hair near the skin surface. Nits are glued securely to hair shafts and for this reason can be very difficult to remove.
Head lice and pubic lice eggs need the warmth and high humidity that is found near human skin to develop properly. If nits are removed from this warm, moist environment they die. This is one reason why it is less important to treat the whole house, bedding, furniture and so forth because lice in general don't survive for long away from their host. Instead control efforts should be directed at live lice and live eggs on the infested individual. This is best done with nit picking and medicated shampoos or lotions.
Effective lice control begins with nit removal. Nits can be either physically removed or crushed. Lice combs do a good job of crushing nits in place or if lice combing is combined with one of the nit-loosening lotions you can actually remove nits without pulling hair out! See Selecting The Best Lice Comb for more information.
When young lice hatch they leave behind the empty egg shell still attached the hair shaft. This empty shell can remain attached for weeks, or even months, so as the hair grows the empty shell moves further and further from the scalp. Therefore any nits found further than about 1/4" away from the scalp have probably already hatched or are dead. This rule-of-thumb may not apply, however, in very warm climates where recent research found that lice will occasionally lay viable eggs further out on the hair shaft. Color is also a good way to distinguish empty or dead nits from live ones. Empty nit shells are white whereas live nits with lice inside are usually darker in color.
Dead nits or empty shells, dandruff, and similar debris can be the cause of many false positives when children are screened for lice. If the screener is inexperienced any of this debris can look like live nits and trigger a positive "find". This is one reason that I do not advocate "no-nit" policies for schools (see What Are School-Based "No-Nit" Policies and Do They Work?). For example, a child that has neither live lice nor nits may still be excluded from school if a screener mistakenly believes they have found "nits" in the child's hair. A better policy is to simply alert parents of a possible infestation and send home information about lice and lice control.
In some countries the term "nits" refers to live lice rather than just eggs. In the US "nits" generally refers only to the eggs attached to hairs. "Nitpicking" or "nit picking" is the process of removing nits by hand usually with a comb of some kind but nits can also be crushed between fingernails.
Professional-level pest control supplies are generally not available in home and garden stores but can be found at DoMyOwn, our affiliate.
This DK Smithsonian Handbook is an excellent general guide to insect identification (available through Amazon, our Affiliate):
For additional resources see our Insect Identification article.
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