Ladybird beetle (family Coccinellidae, subfamily Coccinellinae) with aphid prey in Iowa. Many species of ladybird beetles are ferocious predators of aphids and other herbivorous insects as both larvae and adults.
Long-horned Borer Beetle: Cerambycidae, genus Callipogon (Belize). This beetle was impressive in terms of sheer size, and it sported an intimidating pair of mandibles. I think I can safely say it was the largest beetle I've ever seen in the wild - about 5 inches (13 centimeters) long, not including antennae. Truly a beast.
Weevil, family Curculionidae, from Belize. The elongated 'snout', characteristic of the group, is used for both feeding and for boring a cavity in plant material in which to lay their eggs.