search with a fine toothed comb
Did you go to a public elementary school when you were growing up? Most likely, if you did, then you are very familiar with the technique of having your head checked with a fine toothed comb.
Elementary schools can be prone to outbreaks of head lice- lots of kids in crowded places make it easy for lice to spread. Thus, elementary schools often make a practice of doing head checks at least once a semester, in order to help prevent and control the spread of lice.
Searching through the child’s head with a fine toothed comb is the easiest way of doing the checks (as compared to bare eyes or using straws). The teacher or school nurse will just simply sit the child down and run the comb through his hair, looking at the scalp for signs of lice. The method allows the checker to separate hair into parts easily and also keeps the child calm because combing their hair is normal.
To do a lice check with a fine toothed comb, start in the middle of the head. You'll want to make a part straight down the center from front to back. Then take the comb and pull the hair away from the scalp slowly, looking at the skin for the bugs, nits and other signs of lice.
If the area is clear, take the comb and run it around the crown of the head, bringing the all hair that grows out of the area onto the top of the head. Make sure to comb through it lightly before you pile it on top. Then take a look at the scalp exposed on the part line again for any signs of lice.
If this area is also clear the last places you should be sure to check are behind the ears and at the nape of the neck. You should run the comb down the neck line lightly again.
A large toothed comb is a completely useless tool for this procedure, because the fine teeth will usually separate any lice from the hair, or at least make them spring (they're jumpers!) off of the head. It also makes it much easier to make parts in childrens' hair because their hair is much thinner than an adult’s. Obviously, it's not a fail proof method but it works most of the time.