Often pustules form where lice bites occur and a severe skin reaction can develop. The louse is remarkably adapted for attachment to coarse body hairs. Usually it is found in the pubic and perianal areas, but it has been found on other body areas including the eyebrows and eyelashes. It is most unusual to find the crab louse anywhere but on the host, unless the louse is rubbed off or is carried off with a body hair. It dies after 24 hours if it is not attached to a human.
Eggs attach to the base of hairs and require a week to hatch.
A newly hatched louse grows to adulthood in about 3 weeks. The adult may survive for a month or so on the host. Crab lice are usually transferred from person to person through sexual contact. Some transfer may occur where two people sleep together or maintain other somewhat prolonged bodily contact. Although various writers suggest transfer might occur in other ways, data do not support such contentions.