What are the features of pediculus humanus capitis (head lice) in pediculosis and pthiriasis (lice infestation)?

Updated: Aug 16, 2019
  • Author: Lyn C C Guenther, MD, FRCPC, FAAD; Chief Editor: Michael Stuart Bronze, MD  more...
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The head louse (see the image below) is the most common of the 3 species. The average length of the head louse is 1-2 mm. Female head lice are generally larger than males. [4] The louse is wingless and white to gray and has a long, dorsoventrally flattened, segmented abdomen. It has 3 pairs of clawed legs. Its average life span is 30 days. [4]

The head louse, Pediculus humanus capitis, has an The head louse, Pediculus humanus capitis, has an elongated body and narrow anterior mouthparts. Body lice look similar but lay their eggs (nits) on clothing fibers instead of hair fibers.

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