Cuckoo bees
Female solitary bees live brief lives of frenetic activity – finding a mate, building nests and provisioning their offspring with as much pollen and nectar as time allows. Not surprisingly, more than a few species have figured out a shortcut. Up to a third of all bees are cuckoos, sneakily laying their eggs in the nests of other species. Their young quickly dispatch the host larvae and take all that hard-earned food for themselves. With no need to gather pollen of their own, adult cuckoos are usually smooth and wasp-like, making them some of the hardest of all bees to successfully identify.