What are head lice?

Head lice are tiny wingless parasites that feed off human blood. Lice develop in three stages, nit to nymph to full-grown louse. The average size of a grown louse is 2-3mm, about the size of a sesame seed. Adult lice and nymphs (baby lice) are grayish white or tan in color. They are capable of changing color to camouflage in the hair. After a feeding, a louse’s abdomen fills with blood, giving them a brownish tinge in color. Nits (lice eggs) appear as tiny brown, tan, yellow or white tear-drops firmly attached to the hair shaft. The term nit refers to a louse egg, which may or may not contain a viable embryo. Nits appear darker if an embryo is within. An empty leftover shell will appear clear. Not sure if what you are seeing is lice? Use our Free Online Head Lice Diagnosis form.