There are actually three kinds of lice: head lice, body lice and pubic lice. Head lice are about 2 to 3 mm long and can infest the head, eyebrows and eyelashes. Body lice are 2.3 to 3.6 mm long and live and lay eggs on clothing. Pubic or “crab” lice are 1.1 to 1.8 mm long and are typically found attached to hair in the pubic area but can also be found on coarse hair such as eyebrows, beards/mustaches and armpits.
http://www.cdc.gov/parasites/images/lice/headlice_penny.jpg
Lice start off as eggs or nits, which are oval-shaped, and are usually laid at the base of the hair shaft near the scalp. They are about the size of a knot in thread and can be yellow or white. They usually hatch eight to nine days after being laid.
Once lice (louse is a single parasite) have hatched, they are called “nymphs.”
https://www.empowher.com/head-lice/content/battle-bugs-what-you-need-know-about-head-lice