A few years ago I examined a hundred or so samples of winter hive debris (for
Varroa). I did some of the examination outside where the light was better and
the air fresher. It was March, not likely above 15 oC. There were no apiaries
close by, but a few honey bees would generally appear, obviously attracted to
this debris, even though there was no food reward (maybe some dicarded honey
crystals, but the bees didn't get to harvest them). The debris was mostly wax
chewings, I had taken the larger bee bodies out.
I suppose at that time of year, bees investigating mouldy hives sometimes
discover a "fortune" in honey from a nest in which the bees have died
overwinter. That advantage might maintain a sensitivity to the odour and lead to
attraction at other times of year when the advantage is less.
 
Regarding bumblebees, though, from what I've seen of spring bumblebee queens, I
would expect some kind of visual attractivness as well. Sometimes these queens
will show great interest in small openings.
 
I don't think it's widely known how attractive to bumblebees are the pheromone
traps (Unitrap) used to monitor for Bertha armyworm Mamestra configurata. These
are green plastic containers with a cone entrance. People put them on fence
posts to monitor the moth population in Canola fields to make spray decisions.
The number of forager bumblebees can be enough top become a nuisance (10 per day
in July). I haven't tried the traps without pheromone, pheromone with a
different trap, etc. Because it's foragers, I'd expect the pheromone rather than
the entrance is the attractant.
 
Kerry Clark, Apiculture Specialist
B.C. Ministry of Agriculture
1201 103 Ave
Dawson Creek B.C.
        V1G 4J2  CANADA          Tel (604) 784-2225     fax (604) 784-2299
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