Hill Cuckoo Bumble bee

Also known as Hill Cuckoo Bee, Rock Cuckoo Bee, Rock Cuckoo Bumblebee

Hill cuckoo bumble bees are obligate nest parasites that produce no worker caste, relying instead on usurping the colonies of red-tailed bumblebees. In late spring, heavily armored females infiltrate host underground nests, depose or kill the resident queen, and use pheromones to coerce the surviving host workers into raising cuckoo offspring. Adults can be recognized by their distinctly darkened, smoky wings and thick exoskeletons adapted for lethal subterranean combat.