cuckoo bee

cuckoo bee, any of more than 3,000 species of solitary bees that engage in brood parasitism, a form of kleptoparasitism in which the bees deposit their eggs in the food-provisioned nests of other bees. Cuckoo bees are found on every continent except Antarctica and occupy a range of habitats. The term cuckoo bee is a behavioral descriptor and not a taxonomic group. As such, bees that exhibit this behavior are found in a number of families and genera, including cloak-and-dagger bees (Thyreus, family Apidae), sharptail bees (Coelioxys, family Megachilidae), Triepeolus and Epeolus (both in the family Apidae), blood bees (Sphecodes, family Halictidae), Stelis (family Megachilidae), and nomad bees (Nomada, family Apidae), the largest group of cuckoo bee species. There are even several species of cuckoo bumblebees (Bombus, family Apidae).

Physical description

A large non-taxonomic group, cuckoo bees are diverse in appearance. As insects, they have a body formed of a head, a thorax, and an abdomen and have a set of six legs. Like other bees, they have a pair of large compound eyes on the sides of the head and three ocelli (simple eyes) on the top of the head. Many species have distinctive thick antennae. Some cuckoo bee larvae have large or specialized mandibles to effectively kill other bee larvae.

Cuckoo bees are generally thicker and more compact than other solitary bee taxa, and many have smooth, almost hairless bodies. Some are mistaken for wasps. Given that cuckoo bees do not need to collect pollen for their offspring, their legs lack the corbiculae, or pollen baskets, common among bumblebees and honeybees. The bees range widely in coloration, and a number of species are iridescent. Some cuckoo bees may have evolved to visually mimic their host species.

Natural history

Like most bees, cuckoo bees are solitary, meaning that they do not dwell in social hive communities. They are called cuckoo bees because they lay their eggs in the nests of other bees in a manner analogous to some cuckoo birds (order Cuculiformes), which lay eggs in the nests of other birds. Most cuckoo bees infiltrate the nests of solitary bees, though cuckoo bumblebees exploit bumblebee colonies to raise their young. Some cuckoo bees target a single species of bee host, while others are generalists and can parasitize several host species.

The female cuckoo bee infiltrates the nest of another bee and deposits an egg in a cell designed for the other bee’s offspring. Some species destroy the host egg and replace it with their own. In others, the cuckoo bee larva either kills the other egg or larva directly (and sometimes eats it) or starves it to death by devouring all the food provisioned in the cell. After consuming the food, the cuckoo bee larva pupates and emerges from the nest as an adult. Cuckoo bees often mate in the summer, though they may reproduce year-round in tropical and semitropical climates.

Threats and conservation

Anthropogenic environmental degradation, including global warming, pesticide use, and land-use changes, presents risks to cuckoo bee populations. In addition to their own needs for sufficient habitat and nectar sources, as obligate parasites, cuckoo bees are also affected by declines in their host species.