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Coelioxys: cuckoo bees with weapons

It may surprise you that up to 20% of all bees in North America are cleptoparasites, stealing provisions by laying their eggs on the pollen collected by other bees. According to Bees of the World by Christopher O’Toole and Anthony Raw, the worldwide count of cuckoo species is somewhere around 3700. That means a whole lot of poaching is going on.

Hardworking bees in most families have cleptomaniacs in their midst. The 500 Coelioxys species are parasites in the Megachilidae family, mainly disrupting the nests of Megachile bees, but also known to occasionally prey on other genera as well.

Female Coelioxys are easy to spot because of their pointy abdomens. In fact, their name translates to “sharp belly.” The female uses her abdomen like an awl, drilling a hole into a sealed nest. Once she pokes through, she is free to deposit her eggs inside. When her larvae hatch from their eggs, they dispatch the host’s larvae and live off the pollen. Not the best neighbors.

Not great pollinators

All of this means that Coelioxys are not great pollinators, either. They do drink nectar from flowers, but their paucity of body hair makes for little pollen transfer from flower to flower.

Unless you can see the abdomens of these bees, they are easy to confuse with their hosts. The ones we have here are parasitic on leafcutting bees, and they look similar from a distance. Up close, however, you can see the pointy abdomen on the female, and three sharp spines on the abdomen of the male. Also, many species have reddish legs. Oddly, as a group, the cuckoo bees have some of the most striking coloration and markings in the bee world.

I’ve seen several interesting Coelioxys lately. Shown below is a mating pair that I happened to catch in my friend’s garden. The photo was a total accident. I was focused on the female, but the male moved in as I pressed the shutter. He was so quick, I never even saw him until I viewed the photos. The birds and the bees are not as romantic as you might think.

By the way, in case it seems impossible, say “seal-ee-OX-ees.”

Rusty
Honey Bee Suite

A mating pair of Coelioxys
A mating pair of Coelioxys. The male didn’t waste any time. © Rusty Burlew.

Comments

Nancy Ogg
Reply

Rusty,

LOL I was just going to ask how to pronounce it.

Serious question: what part do you think parasites play in the natural world? Just to keep their host-species from becoming over-populated? Or do these bees in particular do enough pollinating, while drinking nectar, that they benefit the pollinator world overall?

The cuckoo bird puzzles me greatly. Its behavior must be adaptive in some way. Just hard to see how it developed.

Thanks

Nancy
Corinth, Kentucky

Rusty
Reply

Nan,

Wish I could answer that one.

Sharon Klemmu
Reply

All that said, don’t mix up a batch of sugar syrup and share with the hummingbird feeders. Their kidneys aren’t so forgiving. They need a strict 4 parts water to 1 part refined white sugar. Not brown, not molassas, not unrefined organic, not honey. Plain old white sugar. Some people think you have to boil the water. Not so, just hot enough to dissolve the sugar. When it gets cloudy, you have bacteria in there, time to change. My birds and the bees contribution for today.

Ken
Reply

You make me want to be able to identify more and more these ‘other’ types of bees that are out there. Thanks for the nice article and picture… and especially the pronunciation guide. I would have never figured it out.
Ken

Rusty
Reply

Ken,

I collect these pronunciations in a file. I often speak to groups about native bees, which forces me to learn. I love to say Coelioxys—it just rolls off the tongue.

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