I've been studying and thinking a lot about bumblebees since yesterday afternoon, when I discovered that some bumblebees have colonized my compost heap.  I was digging out the composted chicken manure to give away to a gardening friend (and to make room for more chicken poop) when I noticed that several bumblebees were buzzing around the general area.  

The bumblebees looked fretful, which surprised me, since the bumblebees out here are usually pretty passive. (They leave frantic antics to the yellow jackets that should be here soon.)  One buzzed around my face, then wandered over to check out my hands, then hovered and kind of paced back and forth in the air.

"That's odd," I thought.  Then I realized that as I was scooping out composted chicken litter, I could hear the compost heap humming.  And that other bumblebees were entering and exiting through the rear of the compost heap.  And that I was lucky not to have been stung.  And that maybe this was a good place to stop for the afternoon.  (A bumblebee's stinger does not have barbs, so it can sting repeatedly.)

It turns out that bumblebees often nest in compost heaps. (It's cozy in there!)  They like to build their nests in soft, fluffy material.  This makes compost heaps, the insulation in attics, and abandoned mouse holes excellent locations.  Bumblebees don't build a hive per se, and they don't store honey over the winter.  And only about a hundred bumblebees will live in a nest, as opposed to the thousands of bees who occupy a hive.

I'm sure you have already heard about Colony Collapse Disorder, which has affected honeybee populations across the country.  What you may not know is that honeybees are an import to North America.  There are no native honey bees here.  Instead, bumblebees and a few other bee species are our most prolific pollinators.

Honeybees are useful for cash crops like almonds and apples, because they can be moved around to pollinate fields en masse.  Bumblebees are much more difficult to wrangle, and because they live in smaller colonies, it hasn't been practical to domesticate the bumblebee.

Unfortunately although bumblebees haven't been affected by Colony Collapse Disorder, they are falling pray to overuse of insecticide, and to habitat destruction.  Bumblebees are the dolphins caught in the tuna net of pesticides.

Bumblebees here in the Pacific Northwest, come in two basic varieties: one is black and yellow, and one is black and yellow with an orange bottom.  The orange bottomed bumblebees are a little more active and aggressive.  So I'm glad it's the black bottomed bumblebees that have colonized my compost!

If you have bumblebees nesting in the insulation of your house, sadly you will probably need to call a specialist to poison and remove them.  Nesting bumblebees can cause damage to the structure, and can create a fire hazard.  

But if you have bumblebees nesting in your compost heap or somewhere else that they won't be disturbed (by a mower, or by curious children), then you should definitely let them be.  They will go dormant in the fall, at which point you can reclaim your compost heap.

Creative Commons-licensed image courtesy of Flickr user Vicki's Nature