As winter suddenly tightens its grip on us here in Minnesota (it’s snowing outside as I write this, and cold), it’s the perfect time to sit back and do some reading and to reflect on this past summer’s encounters. This means more poetry, more desk work, and more blog posts.
On a recent visit to the college library to retrieve a book about the ecology of tropical bees, I found a slim pamphlet standing near it on the same shelf. Picking it up and opening it, I saw that it was a published lecture given April 22, 1970, at Utah State University by George Edward Bohart. Bohart was an internationally recognized expert on pollination biology and a professor at USU. (Interestingly, his brother, Richard M. Bohart, was another well known entomologist, founder and namesake of The Bohart Museum of Entomology at the University of Califonia, Davis.)
In his lecture, The Evolution of Parasitism among Bees, Bohart discusses the various bee families and the parasitic black sheep among them: from honey-robbing honey bees and resource-pillaging stingless bees to cuckoo bumble bees displacing rightful queens from established nests and myriad kleptoparasites stealing into nests of solitary bees and laying their eggs upon pollen stores not rightfully their own. The trickery involved in parasitism must be quite successful in the grand scheme of things given the abundance and variety of parasitic species. For example, Bohart points out that just among the bees “morphological evidence indicates that existing parasitic lines were derived at least 16 times from non-parasitic ancestors.” (emphasis mine) This lecture reminded me of the interesting parasitic bees I’d encountered, in particular the host prey pair discussed here.
In 2014, I encountered, for the first time, Holcopasites calliopsidis, a brightly colored but tiny parasitic bee that targets the mining bee Calliopsis andreniformis (a fact reflected in the species name of the parasite). At 5 mm in length, this bee is smaller than a grain of rice. A single photograph, mid August, taken as the bee nectared on fleabane (see photo above). I revisited these flowers many times that autumn and the following year and did not encounter this bee again.
This summer I had much better luck. One day in June I noticed a number of tiny bees at several patches of hard-packed, bare ground along the walking trails in the St Olaf Natural Lands. These turned out to be Beautiful Mining Bees, Calliopsis andreniformis. Again, grain-of-rice-sized, though perhaps a millimeter or two greater in length than the aforementioned species. On subsequent visits to the same locations, I was able to get very good photos of these small bees, both the females and the surprisingly different males, with their lemon-yellow legs, face and antennae. According to the description in The Bees in Your Backyard, almost all the bees of the genus Calliopsis are specialist pollinators. Unfortunately, I was unable to observe which particular plants Calliopsis andreniformis had been visiting at this location. (A photo on Bugguide by Heather Holm shows this species on Blue Vervain at a nearby location in Minnesota, and that’s one possibility here as well.)
My good luck continued. Several times while watching the mining bees, Holcopasites calliopsidis showed up, snuffling the ground with their antennae, searching the nesting sites of their hosts. After I had several photographs of Holcopasites calliopsidis, I began to notice that this bee almost always kept its wings tucked under its abdomen. A curious and unique behavior. I haven’t been able to locate any explanation or even mention of this behavior. Considering the bee’s equally unusual colors and patterning, it seems at least plausible that the bee is mimicking the appearance of lady beetle larvae. I’ve included a photo by Katja Schulz of a Convergent Lady Beetle for comparison. If anyone has any alternative theories…I’d like to hear them.
Bohart, G. E. 1970. The Evolution of Parasitism among Bees. Utah State University.
King, S. 2016. A Photographic Guide to Some Common Wasps and Bees of Minnesota. Thistlewords Press.
Wilson, J.S. and O. Messinger Carril. 2016. The Bees in Your Backyard: A Guide to North America’s Bees. Princeton University Press.