Our honeybees were visiting my sawdust pile by the dozen yesterday, so I decided to see if I could track down what they were up to.  The internet was not very helpful --- several people reported seeing honeybees visit sawdust in the early spring when there's nothing else around to eat and they suggested that honeybees were collecting sawdust in lieu of pollen.  The sole piece of data backing up this assertion, though, seemed to be the coincidence that pollen is absent in the wild at this time of year and that this is the only season when people have noticed honeybees collecting sawdust.  While it's possible that honeybees could be tricked into thinking that sawdust is pollen (although at the bee scale, the two substances are orders of magnitude different in size, shape and texture), I suspect that bees who expend their precious winter energy on such a frivolous pursuit would die out in the wild.  Surely there's a better explanation.

Joey was visiting, and he suggested that the bees might be extracting some residual sap out of the sawdust.  We reached down amid our buzzing workers and snagged a pinch of sawdust apiece, then savored the dust.  At first, I couldn't taste anything at all, but after Joey's more discerning palate caught a hint of nutmeg, I thought that I might taste something too.  No proof there, but it made for an interesting photo.

As we continued to watch the honeybees, I became relatively convinced that they were putting something in their pollen baskets rather than sucking the liquid out of the sawdust.  I could see the insects using their legs to push at their pollen baskets, and none of the bees seemed to be sticking out their probosci.  The honeybees also seemed to be expending a lot of effort to kick through the pollen in search of their desired object --- by midafternoon, the pile of sawdust had turned from a volcano into a wide, squat hill.  Despite all this work, when I watched the bees returning to the hive, I couldn't see any sawdust in the pollen baskets, suggesting that the insects were collecting a much smaller substance than sawdust.

Back to the internet I went, this time delving into the scientific literature.  Several scientists repeated the pollen dearth maladaption hypothesis, but none cited any sources.  Instead, I was drawn to a series of articles by Dorothy Shaw, who reviewed over 100 years worth of reports on bees collecting fungal spores all over the world.  Most of the bees gathered spores from rusts or Neurospora, both of which have a protein content comparable to high quality pollen (around 25%).  Although in some cases bees seem to collect fungal spores when other foods are absent, other bees fly right past good pollen and nectar sources to gather fungal spores, returning to the hive with 100% spores in their pollen baskets.  Shaw suggests that the high protein content of the spores makes them a nutrition source comparable to pollen and that collecting spores can sometimes be a better use of a bee's time than gathering pollen since large masses of fungi allow the bees to fill their pollen baskets quite quickly.

I can't prove that our bees are picking through the sawdust in search of fungal spores, but I'm guessing that's the case.  If they're gathering rust spores, I might be able to test my hypothesis next time I look in the hive since scientists have been able to pick out rust spores stored in the brood chamber of honeybee hives by looking for their bright orange color.  I remember seeing bright orange "pollen" in our hives before, and now I wonder if I was actually seeing spores?

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About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.



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