Karl Foord, Extension Educator - Horticulture
One of our early emerging vernal native bees is in the genus Colletes. These bees are commonly called plasterer bees, cellophane, or polyester bees. This is because the bee builds an underground nest and then paints/applies/lines her nest with a cellophane-like plastic material secreted from an abdominal gland. The bee applies this material with her two-lobe tipped tongue. This secretion helps protect the developing bees from fungal disease and acts as a waterproof barrier. It is so effective that ground-nesting species can occupy areas prone to flooding.
I photographed a Colletes bee digging a nest. The nest took several hours to dig which I videoed and then cut out much of the inactivity to create a 5 minute video.
One of today's landscaping rules-of-thumb is to cover bare soil with mulch to both prevent erosion and discourage weed encroachment. This makes sense, however should we reconsider this practice in light of our need to provide nesting habitat for native bees? Perhaps there are areas in the garden or proximal to the garden which could be left open and undisturbed.
Though not specifically stated open soil areas were considered a sign slovenliness, something not tolerated in my upbringing environment. Somewhat along the line of "There are no dirty or lazy Zimmerman's". Something my maternal grandmother used to say.
The two main threats to most pollinators include habitat loss and pesticide use.
You can create a welcoming environment to ground nesting bees by doing the following:
1. Leave bare patches of ground in your garden or yard to help provide nesting sites. It may look unkempt but it is unkempt with a purpose.
2. Plant a variety of bee friendly nectar and pollen rich native plants. A good place to start is "Plants for Minnesota Bees" by Elaine Evans.