Do worker bumble bees camp out?

Rusty Burlew is a beekeeper friend who lives in the same county and writes a regular (at least weekly!) blog about bees.  While these days she writes mostly about honey bees, she knows alot about native bees as well.  Anyway, I replied to a recent post of hers about bumble bees -- Honey Bee Suite / Bumble bee answers ... -- and she asked me to elaborate on whether or not worker bumble bees (the colony females who are not queens) stay out at night rather than going home to sleep.  The short answer -- yes -- was not enough for me.  But rather than fill her comment section I decided to add it to our blog roll.  I can't say how broadly this applies to all bumbles -- it is but a single experience.

Bombus melanopygus is a big boldly colored early season bumble common in Olympia (and the maritime Northwest).  She particularly likes old bird houses filled with old bird nests. We’ve recorded queens as early as the third week of January, but the weather has to cooperate and this soggy winter we’ve reached March and not seen a one.  (To illustrate this blog I'm using some older photos of Nancy's.)

The story.  One spring years ago I was asked to move a bumble'd bird house because of its poor location. The box was originally just a birdhouse ornament on an arbor that also supported the mailbox. Occupied one or two years by some bird, then the bumbles found it. This bee house was jostled with each mail delivery and the occupants were unhappy -- pointedly -- about the jostle. So was the Post Office, who notified the owner that she'd have to alter the setup. Thus, one night I corked and bagged the bird bee house and moved it, to our home a mile away. I'd not thought it all through, and being night and all, I just set the box down on the back shed steps intending to mount it later.

A call brought me back the next day, where many bumbles — at least a dozen, (I didn’t count) — were huddled together where their home used to be. The bumbles were homeless, and the colony was deprived of many of its workers. The huddle looked like a big number in a small bumble colony, (though a tiny number for honey bees). I’d moved a box the year before, and that colony failed. With the failure in mind I went home for my insect net intent on returning the homeless bumbles to their community — and that was my third mistake.

The bumbles had lost their home but not their sense of territory. My effort at netting the homeless bumbles was met with mostly empty netting. But I gained personal evidence that the homeless bumbles were queenless WORKERS who, even in the cool of the spring, had slept out at night, and upon returning “home” were defensive enough still to sting, (painfully!).  I'm still not as skilled as I'd like when it comes to distinguishing male from female bumbles, but a sting is definitely gender specific.

My other mistake was I learned that raccoons thought my temporary location was just for them -- low hanging fruit in a pretty wooden box. I'm sure they were stung too, but for them the wax and honey and larvae were no doubt worth the price of admission. If I’d first visited the shed I’d have known that even if had I recaptured the homeless bees, it would have been for naught.

These days, when asked to move a bumble nest, I try to find other solutions.  Unlike honey bees, bumble bee colonies are annual -- only living months -- so mostly I ask folk to be patient.  Usually bumbles do not reuse an old nest site, because wax moths and carpet beetles and a whole array of hungry camp followers consume the nest even as the colony fades once the new queens and drones emerge.  In hindsight, moving the mail box would have been easier -- but if I had done that, there would have been no story to tell.

Here is video made by Nancy a couple of years ago of B. melanopygus in a bird box: Bumbles in a bird nest box (video)

Glen