Do Your Homework Before Ordering Mason Bees

With honeybee populations declining in recent years, gardeners have been searching for ways to encourage other pollinators to stop by and help out. One pollinator I hear mentioned more and more often is mason bees, and seed catalogs are increasingly offering all kinds of mason bee nesting boxes. They’re cute, these little bee condo things with all those little round holes. So I got to thinking I should buy one. But then I stopped myself, wondering if it was okay to just introduce mason bees to my garden, my neighborhood, Minnesota? I emailed Jeff Hahn, a helpful entomologist with the University of Minnesota Extension Service, and he said he didn’t know a lot about mason bees. But he recommended I talk with Joel Gardner, a grad student who is studying them. Joel didn’t have a lot to say, but what he did tell me made me think I need to do more research before ordering up some bees and a box. (Bees are sold separately.) Native bees, including mason bees, Joel says, are “always a good thing to invite into the garden.” Describing mason bees as “efficient” and “unobtrusive”, he told me that they don’t sting unless you really act like a whack job and grab and squeeze them. Don’t do that, and you can pretty much rest easy while gardening in their presence, even if you get close to their home. What you do need to be concerned about is disease buildup, Joel says. Nests must be periodically cleaned or else fungus spores and mite populations can increase to the point where the nest can be harmful to the bees. If you want to purchase mason bees, you need to be aware of the species you’re ordering since many bees are offered by out-of-state sources. Basically, the mason bee (Osmia lignaria) has two subspecies: Osmia lignaria lignaria and Osmia lignaria propinqua. “Lignaria lives east of the Rockies and propinqua lives west, and introducing them outside their native range should be avoided,” Joel advises. Otherwise, you run the risk of spreading outside pests or diseases to local bee populations. And there could be other problems too. After doing only a little bit more research on mason bees, I found that there is currently a lot of debate about the risks associated with the willy-nilly, nationwide shipment of these popular bees. From what I can tell, it’s just fine to get some. Just be sure to buy the right ones for your zip code. You’ll know you’re dealing with a reputable seller when they offer bees in this way.