Occurrence

Crab lice in natural size

Fig. 9. Twelve medium-sized and large crabs as silhouettes in natural size.

The crab louse has adapted to sparse hair. The scalp hairs are too close (about 220 hairs / cm 2). The pubic hair (about 34 hairs / cm 2) is better suited for crab louse. The crab louse primarily live in pubic hair but is also seen in the hair on the chest and in armpits. On the head, crab louse live in the hair lines (neck and temples), in the scalp hair (thin-haired men), in beards and (especially with children) in eyebrows and eyelashes. There can be many crab lice in the eyelashes – up to 100. When there are many there may be inflammation of the eyelid edge.