Sunday, October 20, 2013

The Mystery of the Funny-colored Bees

If you have a pollinator garden, after a while you become familiar with the cast of characters that frequent it. That is why one late summer day of 2011 I was mystified to notice that some of the bumble bee guests to my garden were looking kind of strange, colorwise. A species of bee called Bombus vosnesenskii, or, the “yellow-faced bee”, which should have a cream-colored face like this: 

was showing up in my garden with an ochre-colored face, like this:

Not only that, but on some of the bees, even the pale yellow stripe on the abdomen was this same orangish color.

My first thought was that it had to be pollen staining. But looking around my garden, I could see no flowers that would stain a bee like that. I thought about any native plants that could cause it, and could come up with nothing. Besides, in looking at the bees, there didn’t seem to be any actual pollen on them, just color.

So I then hypothesized that perhaps the bees were color morphs, meaning insects with a color variation from the norm. Yet I could find nothing in the Bombus vosnesenskii literature that mentioned such a thing. Finally, I considered that these bees could be the result of interbreeding with some other bumble bee species, but again, nothing I read could confirm this possibility.

The summer ended, and with it, the pollinator season. The mystery remained unresolved, a fun riddle that I would occasionally ponder when looking my photos of the “funny-colored bees”.

In late August of the next summer, the same thing happened. Some of the B. vosensenskii coming to my lavender bush had the same weird hue. The mystery deepened in my mind, yet I seemed no closer to finding the truth.

Then in August of this year, some of my neighbors, knowing of my interest in bumble bees, invited me to their garden to see the bees that were “all over our dahlias”. You can probably guess where this is going.

The first thing I saw when I entered their garden was a Bombus vosnesenskii perched on a spent dahlia blossom looking gob-smacked.

The hairs on its face were absolutely loaded with orange pollen. I wondered if the pollen had somehow “jammed its frequencies”, making it unable to function. In that instant I knew I had the answer to my multi-year mystery.

In looking around, a saw several more pollen-stained bees, and the specific dahlia that was causing it. It wasn’t a particularly showy variety, but it did have a few attributes that made it attractive to bumble bees.

First, like all dahlias, it had a composite flower, which means that the centers of the big, daisy-like blooms are actually made up of many tiny flowerets, each of which has a nectar gland its base. Two, this hybrid hadn’t had the nectar bred out of it, or the petals made so numerous that the nectaries were blocked. Three, the pollen on this particular species was particularly thick and plentiful. Pollen is the protein-rich substance that bumble bees gather to feed their larval young.

All good reasons for Bombus to frequent these dahlias, but what these particular bees were after was nectar. And to get at it, they had to stick their tongues and faces deep into the flowers, which put them in contact with the pollen-laden stamens. The effect was similar to sticking one’s face in a bowl full of spaghetti to eat it. Orange pollen was everywhere, staining the bees' hairs.

One of the bees, I noticed, was a very large, beautiful, newly-minted B. vosnesenskii, the hair on her body as sleek and shiny as a black cat’s. She was a next-year’s queen, who would spend the winter in the ground until emerging in the spring to start the subsequent generation of bees.  She was stoking up on dahlia nectar to help her survive the cold, dark months beneath the soil.

No messy eater, she, though. As befits a queen, and with benefit of her long tongue, only the very front of her face, looking like a dainty little powder puff, bore a pale orange dusting of pollen. I was charmed.

I’m always on the lookout for great new pollinator plants, so when I asked my neighbors if I could have a dahlia tuber to plant in my garden, they kindly agreed. With any luck, by next August I will be getting a buzz from watching my own episode of the nature documentary called The Funny-Colored Bees.

Here's some additional video of the B. vosnesenskii queen on a dahlia:


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