To continue our series on the Native Bees of California, we’ll be learning about cuckoo bees! If you know anything about cuckoo birds, you probably know that they lay their eggs in the nests of other bird species, with no intention of raising their own young. When the the cuckoo bird's eggs hatch, the chicks fool the host bird into thinking they're one of their chicks, taking precious food from the host's actual offspring and sometimes even kicking out the other chicks.
Sounds ruthless! As it turns out, 15% of all bees in the world exhibit this behavior, known as kleptoparasitism, which literally means "parasitism by theft". Parasitism is defined as a relationship between two species in which one species benefits while the other gets harmed. Some common parasites for bees include the varroa mite, the hive beetle, and certain species of wasps and flies. But, who would have guessed that bees had to look out for their own kind?!
So, how did this relationship between cuckoo bees and their other bee relatives come about in the first place? It turns out that generations and generations of evolution have led to this way of life for cuckoo bees. It's hard to say exactly when in history kleptoparasitism came about in bees, but today its gotten to the point where many cuckoo bees lack the structures used to collect pollen and have no instinct to build a nest of their own. So in a way, they have no choice but to rely on their bee cousins to raise their young. Can you blame them?
Now, here’s how it all goes down. Once a female cuckoo bee has been fertilized by a male and is ready to lay eggs, she'll fly close to the ground and scan for other bees’ nests to lay her eggs in. When she spots a suitable nest, she'll wait nearby until the unsuspecting host bee leaves for a day of foraging, then she'll enter uninvited. Once in the nest, she'll cut holes in the host bee's brood-cell caps and lay her own eggs inside! Her job is now complete. Her young will have a delicious (and free) meal of pollen and nectar ready for them when they hatch into larvae. When they do hatch, the larvae use their strong mandibles--a fancy word for jaw--and kill the host bee's eggs or larvae in the cell. The host bee doesn't even know this whole process is happening until it's too late.
You might be wondering, what do cuckoo bees look like, and have I ever seen one? Chances are, you have. They often parasitize bees closely related to them. This fascinating group of bees are quite diverse in their appearance, and look notably different compared to their more popular bee cousins. Some cuckoo bees have very hard, almost armored bodies, with spines and sharp mandibles. Some can even deceptively resemble wasps, such as those in the Nomada genus. Even within one species, they can vary in size given the environment they did their metamorphosis in. If you're wondering what you can do to stop cuckoo bees, the answer is nothing. Kleptoparasitism in bees is a completely natural behavior and isn't a threat to overall bee populations and health. So, just let them bee!
We hope you enjoyed this introduction to cuckoo bees. Stay tuned for the next installment of the Native Bee Series, where we cover the fascinating life of leafcutter bees.
Until next time, bee well!
Frankie, Gordon W., Thorp, Robbin W., Coville, Rollin E., Ertter, Barbara. "California Bees & Blooms: A Guide for Gardeners and Naturalists". Berkeley: Heyday, 2014. Pp. 112-125.
Written by Zach Parlee
Planet Bee Educator, Staff Writer and Community Outreach Manager