Cooperative Deception: Beetles Trick Male Bees Into Thinking They're a Female Bee.

Leslie Saul-Gershenz and Jocelyn Miller found the world's first example of "cooperative, aggressive mimicry" (basically impersonation by not just one, but a bunch of individuals) among insects:

Clusters of blister beetle larvae mimic female bees in an act of deception so successful that male bees try to mate with them and bring them back to the nest. There the larvae live in the lap of bee luxury by receiving free food and shelter, according to a new study.

Scientists believe the behavior is the first known example of cooperative, aggressive mimicry among insects. Cooperation is involved since the larvae stack up on top of each other and work as a unit to mimic just one female bee. The act is aggressive because, once in the bee’s nest, the sneaky parasites either eat the egg or the bees' hard-won food.

Link - via Our Strange World