Head lice, Pediculus humanus capitas, are small insects, about the size of a sesame seed, that infest human hair and feed on blood from the scalp. While they don’t spread disease, their movement can cause a tickling sensation and their bites can by itchy. Scratching leads to irritation, scabs, and open sores, which can sometimes get infected.

Head louse. Photo credit: Gilles San Martin/flickr

Did You Know…?

• By the numbers: There are over 3,000 species of lice worldwide. Head lice only infest humans and specialize on the, well, head.
• No jumping, dropping, or flying: Head lice crawl and spread mostly through head to head contact and sometimes through sharing head gear such as hats and helmets.
• Giving kids a reason to avoid their bath: Clean hair is easier for lice to climb through.
• No “No-Nit Policies”: The U.S. Centers for Disease Control states that No-Nit Policies are unnecessary and contribute to needless absenteeism.

Have questions? We have answers! See our Head Lice – Frequently Asked Questions fact sheet for more information.