Bees that attack honey bees
Earlier this week, Lisa from Oregon wrote to say that some really aggressive black and yellow bees were injuring the honey bees that came to her yard. She likes the honey bees and wanted to know what would attack them.
At first I thought they were probably wasps or hornets of some sort, but then I had another idea: wool carder bees. It was the right modus operandi, the right physical description, and the right time of year. I told her my thoughts and said it would help to have a photo. Truthfully, I never expected to hear from her again, but in no time she sent a pic: a European wool carder, indeed.
Many people in western North America are unfamiliar with wool carders and it is no surprise. They were accidentally introduced to the east coast of the United States prior to 1963, but they first appeared on the west coast in 2007. The most recent distribution map I have seen shows an “H” pattern across the continent. They are spread up and down the two coasts, and the coasts are connected by a band that runs across the middle of North America. Based on their adaptability, I expect they will soon be everywhere.
The European wool carder (Anthidium manicatum) is in the family Megachilidae, closely related to the mason bees and leafcutters. The females are solitary, carry pollen in an abdominal scopa, and build their nests in cavities. The female scrapes the leaves and stems of downy plants and carries the wool back to her nest to be used as lining, hence the common name “wool carder.” The wool carders are generalist pollinators that forage on a wide variety of plants.
The bees are striking in appearance with bold yellow stripes on either side of the abdomen—interrupted in the middle—and yellow on the legs and face. The males are much larger than the females and can be quite aggressive when they hunt for females or defend their territory. Early in the day you can sometimes find males asleep in the flowers, covered with morning dew.
Not a threat
Are wool carder bees a threat to honey bee populations? Certainly not. Wool carders do not seek out bees to kill. The males simply stake out their territory and then defend it from intruders. No matter what enters his stake—a bumble bee, honey bee, carpenter bee, hover fly, butterfly—the male wool carder chases it off. Usually he just slams into it. Rarely he will do more damage by pulling off a wing or antennae or even spiking the intruder with spines at the end of his abdomen.
Although the wool carder may occasionally take out a honey bee, so do spiders, some flies, hornets, praying mantids, and yellowjackets. It’s just another hazard in a dangerous world. In fact, since our honey bees and wool carders are both of European origin, you can bet they’ve dealt with each other in the past.
How to attract
Personally, I love to watch the wool carders. They are quick, agile, strikingly beautiful, and they can hover in the air. They dart and stop, dart and stop with a characteristic buzz. Unlike honey bees, the couples mate in the flowers, and although the bees are hard to photograph, if you are patient they will rest on a flower or leaf so you can get a quick shot.
If you want to attract wool carders to your garden, one of the very best plants is lamb’s ear, Stachys byzantina. It has both woolly fibers and attractive nectar. They also like salvia, catmint, lemon balm, birdsfoot trefoil, lavender, and plants in the Scrophulariaceae family such as Verbascum (mullein).
As soon as I got Lisa’s message, I went looking for wool carders and found them in the chicken yard circling a patch of lemon balm. Although I have lots of pollinator housing, I’ve never seen them use it. I’ve heard they prefer offbeat locations, ones we humans can never predict.