Arachnids

Sarcoptes scabei. Adult female mite, ventral view (unstained, low power). Specimens of these mites are usually recovered in skin scrapings. Of the four pairs of legs, the anterior pair are stubby and well separated from the second pair. Both anterior pairs terminate in delicate, stalked discs; the posterior pairs have long hairlike bristles; in males the two anterior pairs and one of the posterior pairs end in stalked discs and the fourth pair in hairlike bristles. Females typically measure 330 to 450 µm long by 250 to 350 µm in breadth; males are smaller, 200 to 240 µm long by 150 to 200 µm. The dorsum of the body in both sexes is covered with posteriorly directed spines.