“Ground bee” season is officially here, but before we get any further, let’s clear up a few things about these insects. Ground-nesting bees get a lot of undeserved blame for stings that they simply aren’t responsible for. Despite their claims, many folks have probably never been stung by an actual “ground bee”. Every year I get plenty of calls about “angry stinging ground bees” in late summer, but these are almost always ground-nesting yellowjackets (Vespula spp.). Undoubtedly, if you stumble into an in-ground yellowjacket nest, you’ll be forced to make a hasty retreat from the area as the colony defends itself. But those aren’t bees…
While yellowjackets and bees are related (both belong to the insect order Hymenoptera along with the ants and sawflies), they belong to completely different families. From a standpoint of taxonomic classification, mixing up yellowjackets and bees would be like confusing dogs for cats, raccoons, or walruses (all belong to separate families within the mammalian order Carnivora). We do technically have social, ground-nesting bees that can be ornery if disturbed (i.e., bumble bees), but folks generally recognize bumble bees by their large size and robust appearance.
So what about these other “ground bees”? Most bees (about 2/3 of all bees) are actually ground-nesting species. In the Midwest, we’ve got around 500 different bee species, meaning there are hundreds of ground-nesting species around us. Our common ground-nesting bees include species of: cellophane bees, mining bees, squash bees, longhorned bees, sweat bees, and others. For the most part, these ground-nesting bees are solitary creatures that live alone, although many nests can occur in the same general area as shown in the video clip below. They often prefer sunny, open areas with thin ground cover or bare, sandy soil and can be common in parks and home lawns.
To a certain extent, solitary bees can be thought of as the insect equivalent of “preppers”. Each bee digs her own nest—a small, bunker-like tunnel in the ground, which looks like an ant hill. Not only do the females have to construct these shelters, but she has to gather all of the provisions needed for her young to survive inside—often in the matter of just a few weeks. The female bees collect pollen and nectar from flowers to create a nutritious substance called bee bread, which they place into small chambers (cells) and lay an egg. Once the eggs hatch, the young bees (larvae) have all the supplies they’ll need to grow and develop in their survival bunkers.
Most of these ground bees have a single generation per year. The adult bees are out and active for a short period of time (often a few weeks), before they’re done and gone for the year. When they are active, our solitary bees can be excellent pollinators and can be more efficient than honey bees in some regards. However, their pollination services often go unrecognized and unappreciated by the general public. While news articles regularly sound the alarm about honey bee declines, we should really be much more concerned about the potential loss of our solitary bee species, as they’re more sensitive to disturbances, pesticides, and other stressors.
If you spot ground bees this time of the year, is there any reason for concern? No. Solitary ground-nesting bees are great to have around. Being solitary nesters, these ground bees don’t have a large colony of adult relatives to defend and they end up being surprisingly gentle and unlikely to sting. Overall, they pose little risk to people or pets. The best thing to do is to simply let them be and appreciate the pollination services they provide.
If you’d like to learn more about Wisconsin’s bees, check on the Wisconsin Bee Identification Guide or the US Forest Service’s Bee Basics: An Introduction to Our Native Bees. If you have solitary ground-nesting bees in your yard and would like to teach others about these amazing pollinators, click the image below to get a sign to laminate and post: