Bees May Not Be What You Perceive: The Unique Behavior of Cuckoo Bees

    When thinking about bees, most of us imagine social bees, living in a hive, which make honey, and have stingers. The domestic Honey Bee, Apis mellifera, largely influences our perception of bees, but does not give an accurate representation of the 20,000 species of bees known to the world. At least 18% of the world's bees fall into a category of bees called cuckoo bees. This is a behavioral descriptor, as opposed to a taxonomic one. What does being a cuckoo bee mean though? Their behavior is very comparable to cuckoo birds who are nest parasatizers in the avian world; going into other birds nests and knocking the pushing their eggs out. What happens is that these bees will find the nest of a bee with eggs, lay their own eggs in the nest, then either eat the eggs of the inhabitant or leave them for their offspring to eat, after hatching. 

    For a female cuckoo bee to find a nest, she must be careful. What she does to find a nest is she waits for a female bee to leave her nest, so that she may enter the nest and lay her own eggs in place of the other bee's. Once the eggs are laid, she is free of responsibility and can feed herself on nectar as she needs to. Her young will rapidly grow, enabling them to out compete the young of the host bee and ensuring the succession of the new generation. Because cuckoo bees do not have to feed anyone except themselves, they do not have adaptions to carry pollen like other bees do. Ergo they do not play a role in the pollination of flowers as most bee species do. Concluding that these bees are harmful to the environment because of this would be an incorrect assumption to make, however. Cuckoo bees typically are not successful unless their host bee has stable and healthy enough populations to support the cuckoo bee young. Seeing cuckoo bees in an environment indicates a healthy community where the bee population is stable enough that cuckoo bees would choose to parasatize that community.

    There are cuckoo bees in most bee families, but there are ways to differentiate them from their hosts. Typically these bees look more like wasps, having little body hair, thick compact bodies, and no coribulae or pollen baskets to carry food back to a nest. Many cuckoos are irridescent in coloration, but there are some species which have evolved to visually mimic their host. This group of bees is highly diverse, with some species being specialists, targeting a specific species of bee and other cuckoos being generalists. Coelioxys rufitarsis, parasitizes, Megachile perihirta, which is the common leaf-cutting bee. Typically, these bees will parasitize two to five different species of bees, but other ones, such as this species, will specialize on a specific kind of bee.

Jaime Pawelek, Rollin Coville, via UC Berkeley Urban Bee Lab

W.S. Cranshaw, via Colorado State University Extension

    Cuckoo bee larvae differ from the large of most solitary and social bees, with an overall larger size and specialized mandibles, which can be quite large for eating the other larvae, if their mother does not eat them before leaving. Either way, these young are prepared to develop into sneaky, solitary, indicators of a healthy bee population. Even if it is at the inconvenience of their neighbors, as long as there is a prominent bee population in a region, cuckoo bees will follow them closely behind.

    Bees are incredibly diverse beyond the world of honey bees, which we are most familiar with. Take some time to be like a cuckoo bee and lie low to the ground, observing the nesting behaviors of your pollinator neighbors. Even though you are not planning to leave your young in their nest, their future may be dependent upon the conservation of the bees that cuckoo bees parasitize.

References:

Cranshaw, W.S. (2012, December). Leafcutter Bees. CSU Extension. https://extension.colostate.edu/topic-areas/insects/leafcutter-bees-5-576/

Cuckoo bee. Britannica. https://www.britannica.com/animal/cuckoo-bee

Lindber, H. (2017, December). What do you really know about bees? MSU Extension. what_do_you_really_know_about_bees

Pawelek, J. Coville, R. Cuckoo Bees. UC Berkeley Urban Bee Lab. http://www.helpabee.org/cuckoo-bees.html

Sneaky Thieves. Washington State Department of Agriculture. https://agr.wa.gov/departments/insects-pests-and-weeds/insects/apiary-pollinators/pollinator-health/bee-atlas/native-bees/cuckoo-bees