The cuckoo bumble bee Bombus rupestris is one of several species examined in a study on cuckoo bumble bees that appears in a new special collection in Annals of the Entomological Society of America on rare interactions among insects and between insects and plants. Such bumble bees, which parasitize other social bumble bee colonies, are understudied, but researchers suggest they have “unrealized potential to reveal processes of coevolution between social parasites and hosts.” (Photo credit: Flickr/S. Rae, CC BY 2.0)