Lousology 101

Images & Biology of Head Lice

• Nits (the eggs of the head louse) are small yellowish-white, oval-shaped eggs that are “to the side of a hair shaft glued” at an angle.
• Nits must be laid by live lice.
• You cannot “catch nits.”
• Once laid, it takes 7-10 days for a nit to hatch, and another 7-10 days for the female to mature and begin laying her own eggs.
• Head lice are clear in color when hatched, then quickly develop a reddish-brown color after feeding.
• Head lice are about the size of sesame seeds.
• Head lice have six legs equipped with claws to grasp the hair.
• Head lice are crawling insects. They cannot hop, jump, or fly.
• Head lice do not thrive on pets.
• Head lice are small, wingless insects which feed on human blood. They need human blood in order to survive.
• Head lice live for approximately 30 days on a host and a female louse may lay up to 100 nits (eggs).
• Head lice off of their human hosts will starve. The NPA suggests that, in most cases, a head louse will not survive for more than 24 hours off of its human host.

Images below appear courtesy of Rick Speare

Images below appear courtesy of William B. Swain

Images below appear courtesy of Dr. Gaetano Scanni

Head Lice of Different Sizes