Black Pollen Day

honey bee collecting coffee grounds in pollen baskets

Arizona honey bee collecting coffee grounds in her pollen baskets.

Some bees eat coffee when they get desperate. I suppose some people do, too. We usually think that bees are always gleefully buzzing flower to flower, happy as ducks in water. But when food is scarce, anything goes. When my niece, Monica King, sent a picture of one of her honey bees collecting coffee grounds in lieu of pollen, I was impressed. It’s a great photo. Let’s take a closer look.

Close-up: Honey bee with coffee grounds on corbicula

Three things to notice. The tiny wad of pollen is tightly bound to the bee’s leg – it must have been stuck there intentionally by the bee; the bee has a bit of black dust on her abdomen; the pollen is black – that’s an unusual colour for a pollen pack. What’s going on here?

Last week, there was frost in southern Arizona where my niece lives. This wrecked most of the winter wildflowers, so yesterday this bee was one of many seen working the compost pile’s coffee grounds. Bees try to forage whenever the weather allows – even if flowers aren’t available. Monica found her bees gathering coffee granules. They were packing the bitter caffeine nuggets onto their legs. A couple months earlier, her sister in Florida had photographed two honey bees on a hive lid – one with orange, the other with black pollen. (Orange and black pollen in October – just in time for Halloween.) I tried to guess what Florida flower might yield black pollen, but couldn’t figure it out. Now we may have the answer. The bee with black pollen was likely carrying coffee, not real pollen.

bees arriving with pollen in AlbertaPollen is typically yellow or orange. I don’t think that I’ve ever seen red pollen – but I’m colour-blind, so I might have seen it but mistook it for green. Fireweed (which grows here) yields a rare blue pollen. Light green, brown, and gray/white are also seen, but black pollen is as rare as hen’s teeth. (Click here for a guide to some common pollen colours.)  Yellow and orange are the proper colours of pollen on posters at Save the Bees rallies. You can see correctly-coloured pollen in the photo above. I always get optimistic when I see scenes like this in Calgary in April.  The colony was still wrapped for winter (the wind had begun ripping the winter protection), but the bees had found pollen and they were their usual happy selves.

When bees get desperate, they scavenge almost anything similar to pollen (for protein) or nectar (carbohydrates). I’ve seen bees collect all sorts of odd stuff. People  have noticed honey bees rolling around in seed dust at bird feeders. Years ago, we were puzzled by bees that visited sawmills. They spent a lot of time hovering around the wet, freshly cut timber. Occasionally the bees lit and then sucked at the wood or moist sawdust. Other times they dove into it and got dusty.

 Sawdust, birdseed, coffee – they’re not necessarily bad.  Bees sometimes need salts and minerals beyond what they find in flowers. Often they don’t bother to stuff the pollen substitutes into their corbiculae. If the stuff doesn’t stick to the bee’s hairy legs, she may dive into the powder so that enough dust sticks and is carried home. Back at the hive, other bees pull it off and put it to use.   Monica’s picture clearly shows that the bee in the photo has tucked coffee to her leg – just a bit of her back is also covered in black dust.

Monica also sent this video clip of how the bees fetch coffee grounds.

They look agitated. (Too much caffeine?) It looks as if they are ‘rolling around’ in the coffee grounds.  But if you focus on one bee at a time and watch her, you may see that she is packing coffee into her corbicula as well.

 I wonder how the brood reacts when caffeinated low-protein grounds are mixed with honey and fed to the larvae as bee bread. Scientists recently showed that bees prefer nectar that has low levels of caffeine over nectar that has no caffeine in it. (Citrus nectar, among others, contains naturally occurring caffeine.)  Tests indicated that a bit of caffeine is attractive – probably as a stimulant – when mixed with test sugar syrup. But mixing in too much repelled the bees -they don’t like strong bitter flavours. The same experiment (reported in Cell journal) claimed that when honey bees received caffeine-laced food, they danced more rapidly and communicated with more colleagues than average bees. If coffee grounds collected by desperate bees visiting compost ends up in the mouths of bee-babes, the house bees may have a daunting task controlling their super-charged little angels when they emerge from their cells as young, highly-caffeinated adults.

About Ron Miksha

Ron Miksha is a bee ecologist working at the University of Calgary. He is also a geophysicist and does a bit of science writing and blogging. Ron has worked as a radio broadcaster, a beekeeper, and Earth scientist. (Ask him about seismic waves.) He's based in Calgary, Alberta, Canada.
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4 Responses to Black Pollen Day

  1. Emily Scott says:

    There is some pollen which is black – poppy is one. Sad to see bees wasting effort on collecting coffee grounds – why are people leaving them outside? This is one reason why I think a properly cold winter can actually be better for the bees, as it stops them going outside trying to find nectar and pollen which just isn’t available.


  2. Pingback: A Look Back at 2015 | Bad Beekeeping Blog

  3. Pingback: Black ‘Pollen’ in March | Bad Beekeeping Blog

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