Bees and climate change

Credit: Flickr / asplosh

As the ‘Bees and Sustainable Gardening’ reference person for West Coast Seeds and as a bee educator/advocate, I field many queries about bees. Lately there’s a lot of buzz about Blue Orchard Mason bees—especially lots of questions about bees not emerging, even in warm weather.

The Blue Orchard Mason Bee normally begins to come out/emerge when daytime temperatures reach 14° C. Unfortunately our humble, hard-working mason bee is generally not able to withstand temperatures below minus 10° C. Throughout much of the Lower Mainland, winter temperatures fell well below that—with temperatures (including wind chill) getting to -20° C.

So, if you kept your bees in an unheated garage or woodshed or even perhaps still in their nests in their garden location, you may have unwittingly exposed them to freezing. Sadly, human made nests do not offer good protection in these unusually cold circumstances; even bees purchased from reputable suppliers were affected. And, it’s impossible to tell a frozen bee from an alive one while in the cocoon.

Climate can be brutal and unpredictable, and even experienced mason bee “ranchers” were caught by surprise the last two to three years by a warm start to spring followed by a dramatic drop in temperatures.

Until fairly recently, March was just fine to put the mason bee cocoons out into the garden or orchard. Now, mid-April seems more prudent.

Those who put bees out early saw the males emerge but then female emergence was delayed several weeks by cold weather. By the time things warmed up enough for the females to come out, the males were dead.

Events like this underscore the fragility of our ecosystem.  A cold spring equals bee deaths, which reverberates throughout nature; few berries, hungry bears and higher food prices… so! I recommend heading the problem off at the pass: at the end of June, when I see the adult mason bees are no longer active, I take my nests indoors, careful to tip them with the entrances pointing up so that the larva will fall back onto the pollen mounds that the adult female bees left for them.

In October, it’s best to take the nests apart and clean them out. (I wash the cocoons very gently and carefully, then store them in an airtight container in the refrigerator.)  At the beginning of March, I monitor weather conditions waiting for an opportunity to put the cocoons out by the clean and tidy nests. Again, the last couple years it hasn’t looked right until the first week or two of April.

is a certified beemaster and beekeeper, heavily involved in food security issues in Richmond and beyond. A member of the BC Association of Master Gardeners, Brian spent three years as seed manager for West Coast Seeds. Brian guest lectures for Gaia College’s Growing Food in the City certificate program, operates pocket markets in Richmond and teaches young people about honey bees as well as native types. He offers classes in grafting fruit trees, food preserving and other farm skills.