Pests of Medical Importance



Human lice are wingless ectoparasites of people. There are three types of lice that typically affect people, human head lice, body lice, and crab lice. These species differ not only by location on the body, but the claws are adapted to specific hair diameters. Lice spend their entire life cycle on their hosts.

Head lice feed exclusively from the scalp of people, while body lice are found on the body. Body lice diverged from the human head louse around 100,000 years ago. Head lice do not carry pathogens that cause disease. Body lice, however, can carry epidemic typhus, trench fever, and relapsing fever. Crab lice are generally found on pubic hair, although they can be found on eyebrows and eyelashes as well, but are also not pathogen carriers.


Penn State Extension Resources


Itchy, Itchy!

Got head lice? Eliminate head lice with IPM

Human lice

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