Ground-nesting Bees Are Solitary and Often Stingless

Ground bees — Surprisingly, most of the bees in North America are solitary and about 70 percent of them live in the ground. Jean and Fred/Flickr (CC BY 2.0)

You think you know what bees are all about: They make honey and live in hives with a queen and sting you sometimes, right? Well, all this is true about some bees, but just like there are lots of different kinds of rodents — big ones and small ones, species that live in trees and underground, species that love to nest together and others that just want to be left alone — Earth is home to approximately 20,000 species of bees, and they're all a little different.

Bees are our most important pollinators, and a lot of places in the world are home to eusocial bees like the ubiquitous western honey bee (Apis mellifera) that was probably originally native to Asia, but has spread to every continent except Antarctica over the centuries. Industrial agriculture operations spend millions of dollars every year renting hives to pollinate their crops to increase yield.

Honey bees live in hives with a queen who's in charge of procreation in the colony. But most bees on the planet aren't honey bees — in fact, there are only a handful of honey bee species in the world. However, every continent has its own native bees, which occupy most spots on the planet, from the Arctic, to deserts, tropical forests, grasslands and most places in between. In North America, there are around 4,000 species, with new species being discovered all the time. Surprisingly, most bees are solitary, meaning that each mother bee provides for her own nest, and about 70 percent of native bees live in the ground.

"You could think of solitary bees as hard-working single moms, working nonstop from sun-up to sun-down to provide pollen and nectar, in the form of little loaves, that they provide for their young," says Clay Bolt, a natural history and conservation photographer specializing in native bees.

Nesting Underground

Ground nesting bees like a variety of different ground types, but most often they nest in dry, hard-packed soil, similar to places where you might see an ant's nest.

"They will often be seen along the sides of paths, or bare patches of soil that most people take for granted," says Bolt. "They can also nest beneath leaves — an important reminder of why homeowners should leave a patch of leaves in their yard — or in rotting wood. Most don't destroy wood, or excavate cavities in wood, but rather use pre-existing insect burrows."

A solitary bee nest is a tube about 6 inches (15 centimeters) long, excavated in dry soil by a female bee. There are many challenges that come from nesting in the ground: predators; moisture and flooding; intense heat; the challenges over overwintering; nest disturbance by people, vehicles, other large animals; and pesticides are just a few. To deal with the natural threats that ground nesting bees face, they've developed many strategies to protect their young. Bees line their nests with things like hard-packed soil, bits of cut leaves and masticated flower petals. One genus of ground nesting bee is known as "cellophane bees" for the clear, waterproof stuff they paint onto the walls of their nests. Whatever the material, nest linings keep the young sufficiently dry and retain the integrity of the nest.

They're Often Stingless

Because most of us associate bees with a honey bee's propensity to sting, we often try to get rid of bees or yellow jackets (which are actually wasps) in our yards and around our houses. However, ground nesting bees aren't dangerous. Many solitary bees are very tiny — smaller than a grain of rice — and therefore too small to sting. If they are able to sting, their venom is too weak to do much damage.

"Solitary bees rarely sting," says Bolt. "The most aggressive of all bees are honey bees, because they have a hive to defend. Solitary bees, on the other hand, have everything to lose if they sting someone or something and get killed in the process. If the mother dies before the young has been provisioned then her lineage ends. The bees most commonly seen circling around solitary bee nests are mostly likely males, which actually can't sting."

Ground Nesting Bees and Your Lawn

It's difficult to be a solitary bee in a world full of manicured lawns. Homeowners often view these ground nesters as a nuisance, and use pesticides to get rid of them. But, killing these pollinators with pesticides is dangerous for their populations, which are already dwindling.

It's important to note that solitary bees are not much of a threat to lawns and turf. You can continue to mow your lawn, play and picnic as usual right next to the bees, but if there are many nests in an area, you might want to avoid that spot for one to two months while the bees are nesting. If you must dissuade the bees from nesting, don't use a pesticide — heavy watering can encourage them to pack up and pick another spot.