Head lice infect the scalp and hair and can be seen at the nape of the neck and over the ears. Head lice spread easily and quickly but do not carry disease as other lice do.

This photograph shows a "nit" or tiny white egg sack attached to the shaft of a human hair. (Image courtesy of D. Scott Smith, MD, MSc, DTM&H)

This photograph shows the "nits" or tiny white egg sacks attached to the hairs. Schools often insist that these be entirely removed before a child returns to school.

This is a photograph of a head louse emerging from an egg. Head lice have become an increasing problem in schools and day care centers. Some grade schools have started programs to examine children for head lice.

This is a photograph of a male Pediculus humanus var. capitis, a head louse. Head lice have become an increasing problem in schools and day care centers. Some grade schools have started programs to examine children for head lice.

This is a photograph of a female Pediculus humanus var. capitis, a head louse. Head lice have become an increasing problem in schools and day care centers. Some grade schools have started programs to examine children for head lice.

This is a close-up picture of lice egg sacks (nits) on the hair. They cling to individual hair shafts. (Image courtesy of the Centers for Disease Control and Prevention.)