The diagnosis of human phtiriasis (often referred to as the "crab" or the "pubic louse") can be more difficult than other types of pediculosis (Pediculus corporis and Pediculus capitis) because this insect has a smaller body of 1.2 x 0.8 mm, may be lighter in color, not as mobile and therefore harder to see to the naked eye. Can dermoscopy aid to perform a better analysis of the skin? The clinical experience developed in two patients gives an affirmative answer, moreover adding useful information of insect and its eggs already known to entomologists but never used in dermatological diagnosis. The identification in vivo can distinguish Phthirus pubis from other skin signs while the conical shape of the operculum and the wide fixing sleeve of egg to hair, tells what species of louse is infesting, even if the insect is unavailable or nits are elsewhere from the pubic area. Entodermoscopy, provided that dermatologists have some knowledge of entomology, therefore promises advantages over standard microscopic examination.