…even the insects in my path are not loafers, but have their special errands.
~Henry David Thoreau
About two weeks ago, we took a hike at one of our favorite springtime destinations, Johnston Mill Nature Preserve, one of the many wonderful properties owned and managed by the Triangle Land Conservancy. We have been impressed and amazed by the variety and abundance of spring wildflowers that carpet the ground here and were hoping to catch the flowers at their peak. This year, we were lucky, and hit the trout lilies at their height of bloom. While Melissa and her sister went off for some exercise with a brisk hike along the trail, I did my usual snails pace walk/crawl, camera in hand, looking for anything interesting along the way.
Many flowers (especially the spring beauties and trout lilies) were still closed due to the chilly temperatures and overcast skies. But the windflowers were doing their thing, quivering in the slightest breeze, flowers (with their white sepals, no petals) facing skyward.
After an hour or so, the sun started to shine and the flowers opened, beckoning the early season pollinators.
I was hoping to observe and photograph some of the elusive pollinators, so I was alert for any movement near the open blossoms as I eased along the trail.
I searched for spring beauty bees, a specialist on their namesake spring ephemerals with pink pollen. I did capture one photo of what I think is a spring beauty bee (see the first photo of spring beauty above), but the bee on this plant looked different.
I started seeing this bee on many plants, especially the abundant trout lilies.
At one point along the trail, we noticed a concentration of these bees flying low over the ground. I knelt down to photograph one on the leaf litter, and as I focused for another shot, it disappeared into the leaves. That’s when I noticed a nearby mound of soil with a pencil-sized hole and a pair of large eyes peering out at me.
And this is where my photos of this amazing creature end, but its fascinating story begins. We watched these bees for quite awhile and discovered what looked like a colony scattered over a large swath of ground in the floodplain of the creek. Many of the entrance mounds to their burrows were partially hidden in the leaf litter, but all were about the size of a golf ball with one hole near the top. The bees appeared to be going in laden with pollen and then exiting free of that cargo, presumably having stored it for their soon to be developing young. That night, after trying to identify the bees with various online resources, I uploaded a few images to Bug Guide and heard back the next day from a couple of their helpful experts. These are a type of plasterer bee (also called cellophane bees) – the experts best guess is this one is Colletes inaequalis, the unequal cellophane bee. The reason for their groups’ unusual common name is that females produce a secretion from their abdomen that is a type of polyester which becomes the brood cell for their young. Though these bees are solitary (a female digs her own burrow and tends it herself), they tend to nest in aggregations (sometimes in groups of hundreds or more nests), especially in sandy soil on south-facing slopes. She creates several brood cells that resemble small plastic bags in side chambers of her one-foot deep tunnel, stocks them with a liquid pollen and nectar mix, and then suspends one egg above the food larder in each cell. The more I learned about this species, the more fascinating it became. Some researchers are studying the brood cell material to see if it can be synthesized for a biodegradable plastic! To learn more about the biology of this fascinating bee (and to see some amazing photos of an excavated nest chamber and brood cell) visit these two links – Polyester bees: Born in a Plastic bag and Nature Posts: Bees That Dig Holes in the Ground.
There were quite a few references to people being alarmed at finding aggregations of these bees in their yards, but there is no need to be concerned about them as they tend to be quite docile. They are among the earliest bees to be(e) active and then only for a few weeks before the entire colony is reduced to the developing larvae and pupae being underground until the following spring. Plus, they are important pollinators of early spring wildflowers, so let them be(e). One other interesting note, and an indicator of how climate change is impacting species large and small – researchers using historical museum datasets and more recent bee-monitoring data looked at the timing of spring emergence of this (and several others) species of native bees. Over the past 130 years there has been a significant shift toward earlier spring time emergence with an average ten days earlier now than in the late 1800s. That trend has been most pronounced in the last 40 years. With all these bees are doing for us (pollination services), telling us about our changing climate, and the possibility of synthesizing their unique polyester secretions, we should appreciate these fascinating master burrowers and protect them and their kin.