Head Lice

Introduction These human-infesting lice receive their common names from the areas of the human body, which they typically infest. It must be realized that an infestation of any of these is a medical problem, not a pest control problem. However, the PCO can perform a valuable public service by serving as a source of pertinent information to both institutional personnel and individuals. Only the body louse is a vector of human diseases, manly typhus, relapsing fever, and trench fever. These lice are found worldwide and throughout the United States.

Recognition

  1. Head louse are 1/16-1/8" long. Body flattened but elongated in form; head only slightly narrower at the thorax; 3 pairs of Similar legs; tarsi with 1 large claw for grasping round hairs between tibial thumblike process and its opposing claw; abdominal segments without lateral lobes; occurs almost exclusively on the head and attaches its eggs to hairs.
  2. Body louse, are about 1/8" long body flattened but elongate in form; head only slightly narrower at the thorax; 3 pairs of similar legs; tarsi with 1 large claw for grasping round hairs between tibial thumblike process and its opposing claw; abdominal segments without lateral lobes; occurs primarily in clothing and moves to adjacent body areas to feed. And attaches its eggs primarily to clothing fibers.
  3. Crab/pubic louse, are about 1/16" long; body flattened but broadly oval in form; head much narrower than thorax; front legs much more slender than middle and hind legs; tarsal claw large, adapted for grasping flat hairs between tibial thumblike process and its opposing claw; abdominal segments with hairy lateral lobes; occurs primarily where flat hairs are present and attaches its eggs to body hairs.

Habits

  1. Head louse. For all practical purposes head louse occurs only on the head. They are most commonly found above the ears and on the back of the scalp, less often on the entire scalp; rarely are they found on other body hairs such as in the eyelashes. Head lice live continuously on the head area unless dislodged by scratching, hats, combs, brushes, towels, etc. They are commonly transmitted by the direct contact of 2 heads or by combs, hairbrushes, or hats being shared, or by hats being temporarily stored in contact with other hats.
  2. Body louse. Females usually occur along clothing seams where they lay eggs. Males tend to be generally distributed over the inside of the clothing but further away from the body skin. Adults migrate further from the body than nymphs. The infestation must be very heavy before lice can be seen on the outside of clothing. Body lice prefer wool clothing. When feeding, they usually retain their hold on the adjacent clothing an only occasionally will they crawl on the body. Body lice are commonly transmitted by the sharing of infested clothing and/or bedding.
  3. Crab/pubic louse. These lice live continuously on the host. Once a louse settles it does not move much. They feed off and on for several hours at a time and defecate frequently blood and body wastes while feeding. Crab lice are transmitted by intimate or sexual body contact. They are found primarily in the pubic and perianal areas. Prior to puberty, children are usually not infested but if crab lice are present, they are usually in the eyelashes, if infants are infested, the mother should be examined.