The wax blooming beetles Colposcelis microderoides microderoides Reitter and Anatolica polita borealis Kaszab (Coleoptera: Tenebrionidae) are small, flightless beetles living in the Guerbantonggut desert in the northwestern region of China. These beetles were recently found to have wax blooms, and their short life cycle and ease of rearing under laboratory conditions make them excellent models for advanced studies on desert adaptation. To date, dissection has been used for sex identification in these species, whereas a nondestructive method is needed for further studies on sexual dimorphism. Microscopic examinations of pupae and adults revealed distinct differences between the sexes in the 8th abdominal sternites, including the presence of a setose cleft in adult males that is not visible in females, in which the 8th sternite forms a single semicircular plate. The female pupae have a pair of tan papillae and a tan genital orifice, which are absent on the male 8th sternite. These two sexual characteristics can be used to sex live adults and pupae. These methods are simple, nondestructive, 100% accurate, and useful for sex differentiation of dead beetles and some other tenebrionid species (including some pests) in both the field and the laboratory.