Regular readers of this column will know that there are very few species that I don’t like at least a little. I even give ticks a certain grudging respect for the effectiveness of their adaptations. And in a very real sense, my “favorite species” is always the one I happen to be watching at any particular moment.
And yet there are certain species for which I conceive a particular, enduring fondness. Sometimes this is because the plant or animal displays particular beauty, or particular elegance in its evolved form or behavior. Sometimes it’s because the species played an important role in my development as a naturalist. And sometimes, for example in the case of the aster mining bee, Andrena asteris, both reasons apply.
Just over four years ago, October 2, 2021, was early in my development as a student of bees. In the spring of that year, I found myself suddenly, inexplicably intrigued by bees, and resolved to begin learning what I could about them. In early August, I took a weeklong workshop in bee studies at the Eagle Hill Institute in Steuben, Maine. Returning to the Vineyard, I began putting my newly discovered interest and newly acquired skills to work.
In fine weather that Oct. 2, I visited the community garden at Thimble Farm with bees (among other groups) on my mind. I collected one puzzling bee as she foraged on the white flowers of heath aster (Symphyotrichum ericoides), one of several native asters that flourish at that biologically interesting site. The next day, I identified her as Andrena asteris.
It was a significant moment in two ways. For one thing, this was the first member of the large, difficult genus Andrena for which I managed a species-level identification that felt (and indeed proved to be) absolutely solid. Quite a breakthrough! For another thing, as far as I could determine, this species was a rare one on Martha’s Vineyard. My best source for bee information, an exhaustive study of Vineyard bees coordinated in 2010 and 2011 by Paul Goldstein and John Ascher, had found only two examples of this species (out of about 14,000 specimens collected during the study).
That impression of rarity, time has shown, was incorrect. Perhaps the Goldstein-Ascher study didn’t sample the right places to find Andrena asteris. Or perhaps those years were poor ones for this species. But my subsequent experience has shown this bee to be a generally common one on Martha’s Vineyard, indeed one of the most common of the dozen or so species that associate most closely with late-season asters and goldenrods. The fact that it isn’t actually rare, however, has in no way dimmed my fondness for this bee.
Fairly large by Andrena standards, a female A. asteris is about the size of a honey bee. As with all members of this genus, female aster mining bees have facial foveae — distinct, hair-lined grooves running along the side of the face, along the inboard edge of each eye. Fovea form and color are important ID cues for Andrena, and on A. asteris, these features are striking: broad, well-defined, and lined with fine white hair. Each segment on the abdomen is edged with a band of obvious but usually rather sparse white hair; on the first segment, that band is often broken in the middle. Males, a bit smaller than females, are more distinctive, with extensive yellow on the face (an uncommon and almost invariably useful feature for bee identification).
As both the common and scientific names suggest, A. asteris associates closely with asters; in my experience, it is especially fond of aster species with small, white-rayed flowers, though it will visit any kind of aster, and sometimes even goldenrods, which are in the same taxonomic family. Both females and males spend much of their time taking nectar from aster flowers, the females also collecting pollen with which to provision their underground nests.
Where conditions are right, Andrena asteris can be plentiful. A patch of white asters in Aquinnah, where you’d park to visit the shops at the Gay Head Cliffs overlook, has hosted dozens at a time in each of the past several Octobers. This year, I noticed an aggregation of mining bee nests just across the road, in the center of the parking circle. Each nest, a hole in the middle of a tiny tumulus of sand, was conveniently situated close to those asters. But if you watch for a while, nearly any decent collection of asters or goldenrod will eventually attract this bee.
Female aster mining bees, nearly immune to disturbance while they’re working, spin rapidly on each flower they visit, systematically extracting as much nectar or pollen from every flower as they can before moving to the next. Their scopa, or the pollen-carrying hairs on their hind legs and thorax, are usually full of orange pollen. And I’m always happy to see them.
