On the last day of September, I got home from work and did what I do virtually every warm day throughout the year: turned on my camera, and took a swing through our yard to look for insects. Early autumn is one of my favorite times of year for this tradition. For one thing, I’m deeply interested in bees, and this is a time of year when many uncommon bee species are at their peak of activity. For another, I’ve converted our front yard into a meadow, replete with native wildflowers selected precisely to appeal to those bees. It can get interesting!
On this particular day, things were slow to start. Honeybees and the common Eastern bumblebee, Bombus impatiens, were hard at work on our three species of aster and two types of goldenrods. They were joined by many Northern paper wasps and a smattering of butterflies: Huron sachems, American coppers, and cabbage whites. But one bee stood out. Vaguely bumblebee-like, with a chunky body, black abdomen, and yellow fur on her thorax, she might have passed as a very small Bombus impatiens. But the abdomen, instead of being covered in black hair, was bare and shiny, except for narrow bands of pale hair. And her behavior was striking. In contrast to the sedate foraging of a bumblebee, she was in constant, frenetic motion, spending just seconds on each blossom she visited, and vibrating as if with excitement as she swept yellow pollen onto her leg hairs.
With a few decent photographs to work from, and taking advantage of the relatively small number of possibilities late in the season, I readily identified her as Drury’s longhorn bee, Melissodes druriellus. Existing records suggest this bee is uncommon on the Vineyard, and this was only my second time encountering the species. While M. druriellus will visit many types of flowers, experts all agree that this insect favors native composite flowers: goldenrods and asters like those I’ve stocked our meadow with.
Over the next few days, I had the pleasure of getting to know M. druriellus rather well as she made repeated foraging visits to our yard. Photos taken across multiple visits show recurring patterns of wear and wing damage, proving that only one individual bee was visiting. She showed absolute fidelity to just one type of flower: the yellow-centered, blue-rayed blossoms of stiff aster, Ionactis linariifolia. Each visit lasted roughly five minutes, at the end of which she abruptly flew away, presumably to deliver her pollen load to her nest. She systematically mined my entire patch of stiff aster, starting at one end and visiting scores of blossoms as she worked her way to the other end.
As she visited flowers, it looked as if she used her mandibles to loosen pollen grains, then used her middle legs to sweep the grains back onto the voluminous brushes of scopa, or pollen-carrying hairs, on her hind legs. A full load of pollen looked like bright yellow bloomers – what bee lovers sometimes refer to as “pollen pants.”
By Oct. 6, she was having to work harder. Her preferred aster flowers were aging, starting to form seeds instead of producing pollen, and there was considerable competition from other bees for what pollen remained. But she either learned or instinctively knew to focus her efforts on flowers that were still yellow in the center. Once that day, I found her with bare scopa, but she still managed to acquire an impressive load of pollen. Very little seems to be known about the nesting biology of this species in particular, but we can extrapolate from what is known of other species. Like many solitary bees, individual female M. druriellus each dig their own underground nests. Enlarged cells built off the main tunnel — perhaps 10 or a dozen — each receive one egg and a stock of pollen, with each cell likely getting the result of multiple foraging ventures. So, as a very rough estimate, M. druriellus might need to make 50 or 60 successful shopping trips to fully stock her nest.
Of course, I don’t know what she was doing when I wasn’t watching. She undoubtedly had to spend some time in her nest, laying eggs, maintaining the tunnel, and unloading pollen. And it’s possible she was visiting other flowers as well, or that she was exploring at random in search of other resources. But the regularity with which I found her, and the duration of her visits, make 10 visits a day for five or six days seem very possible.
There is a sizable random element in all this: Mrs. druriellus likely stumbled across our yard by chance, and just happened to find a robust population of a preferred food plant, in absolutely prime condition. There’s no guarantee that the timing will work out so happily in the future.
But for now, I have the satisfaction of knowing that I provided an elegant, uncommon insect with exactly what she needed, when she needed it. And I’m hopeful that a year from now, I’ll find some of her offspring sampling our stiff aster — the start of a new local population of this fascinating bee.
