by Austing Gerth
Pollinator expert Heather Holm paid a visit to the native plant center at Prairie Restorations Inc. in Princeton on Saturday, July 8, where she led a guided nature walk to familiarize those in attendance with pollinators native to Minnesota, their importance and what gardeners can do to create habitats that will support native pollinators.
Pollinators are insects that collect pollen from plants, which allows plants to reproduce when the pollen is spread from plant to plant. The insects gather food from the plants during the pollination process, making the relationship a mutual exchange.
The most prominently known pollinator for most people is likely the honeybee, but there are many other types of pollinators (and many other types of bees) as well.
Holm led those who attended the walk around Prairie Restorations’ grounds. The walkers were able to catch and release different types of bees and wasps they discovered as they went. Holm identified their catches and told them about them.
The group found their first pollinators right outside the door to Prairie Restorations’ retail store. They were small resin bees that built their homes in small cavities in the wooden posts outside the building.
Holm explained roughly 30 percent of Minnesota bees nest in cavities, usually pre-existing holes. Many kinds of wasp do as well. The group later found a grass-carrying wasp, which looks and behaves a bit differently from the aggressive stinging temperament usually associated with wasps.
“She is called a grass-carrying wasp,” Holm said, “because she will clip pieces of grass blades and coil them up. … If you see cavities with grass sticking out of them, then that would be a nest of that wasp.”
Holm explained that there are some wasps that are social, which tend to be the more aggressive varieties that often get mistaken for bees and sting people more commonly than bees do. Other wasps are solitary, and they tend to keep to themselves.
“I would guess, unless you’re a beekeeper, the last insect you were stung by, besides a mosquito, is a wasp, and these are social wasps, not solitary wasps,” Holm said.
The hikers got to see the smallest subspecies of bee likely to be found in Minnesota, which pollinates specifically purple prairie clover plants. They learned to be wary of the difference between the brown-belted bumblebee and the endangered rusty patched bumblebee, which are often mistaken for each other. (The rusty patched bumblebee has an orange or rust-colored area in the middle of the brown belt it otherwise shares with the brown-belted bumblebee.)
Hikers also caught and released multiple circuit flies, which Holm explained are mimics of bumblebees. She said the way to tell the difference between them is to look at the lengths of their antennae; flies have stubby little antennae, whereas bees have longer ones. She suggested to look at the eyes, too, because flies have much bigger eyes. Flies also have two wings, whereas bees technically have four, although they are closely set in pairs.
Holm also clued the walkers in on specialist pollinators, which only pollinate one or very few species of plant. The nature of specialists’ relationships to the plants they pollinate will be more easily disrupted by climate change and other factors that could impact populations of either the plants or the pollinators.
During the walk, Holm found at least one plant she recommended people plant to combat this danger: the ground cherry, which supports five species of specialists and produces edible fruit.
Holm is the author of “Bees: An Identification and Native Plant Forage Guide,” which includes sections on bee identification and a section offering guidance on what to plant to support native bee populations.