Distinguish adults of predaceous ground beetles (Carabidae) from plant-feeding darkling beetles (Tenebrionidae) by examining the base of the hind legs. Predaceous ground beetles (left), tiger beetles, and other Adephaga suborder beetles (mostly aquatic species) have enlarged basal segments (coxae and trochanters) on their hind legs; the hind leg coxae completely divide or cover at least the first abdominal segment. On the underside of darkling beetles and other suborder Polyphaga beetles the hind coxae and trochanters are not enlarged and the rear margin of the first abdominal segment is entirely visible. Credit: Packard AS. 1876. Predaceous ground beetle from Guide to the Study of Insects. Trubner & Company. Darkling beetle from Daly HV; Doyen JT; and Ehrlich PR. 1978. Introduction to Insect Biology and Diversity. McGraw-Hill. Used with permission of H Daly
