We know honeybees are expert pollinators. It’s why we’ve come to depend on their services to the degree that we have. And why, by now, we’ve all surely heard the message that honeybees are in trouble and need our help. Even so, they’re far from being the only pollinators around.
In North America alone, there are some 3,600 different bee species. Around 1,500 of those are east of the Mississippi. “Further west we have more like 2,500 species,” noted Matthew Shepherd during the May 2022 webinar, “What Bee Is That? An Introduction to Commonly Encountered Bees of the U.S.”
Shepherd is director of education and outreach for the Xerces Society for Invertebrate Conservation. He’s also a great spokesman for the countless other bees that deserve our attention. What follows are some highlights from Shepherd’s recent “What Bee Is That?” webinar. (You can watch the full webinar recording here.)
Which Ones Are Native Bees?
It’s easy to confuse various native bees with wasps and even certain kinds of flies. As a general rule, bees are usually hairier. Also, although there’s a lot of variation between the thousands of bee species, bees have some method for carrying pollen.
They also have six legs, two pairs of wings and long antennae.
Some of the smallest bees—like certain sweat bees—are only about 0.1 inches long. (Some bumble bees, on the other hand, measure as much as an inch and a quarter long!) There’s a lot of variation in how and where these native bees choose to live, too.
“About 70 percent of our native bees nest in the ground,” Shepherd said. Some of these include specialist bees like sunflower bees and squash bees. Sunflower bees (genus Svastra)—emerge in summer to forage almost entirely on sunflowers.
For their part, squash bees are brightly striped and measure 0.4 to 0.6 inches long. From the Peponapis genus, they’re particularly well-equipped to collect the large pollen grains from squash flowers. As such, they appear in time with the squash blooms. (Leave some bare soil patches near your squash plants, and squash bees will likely move in.)
Mining bees (genus Andrena) are also ground-nesters. There are more than 500 species of these in the U.S. They tunnel into bald patches of earth within grass and emerge in late winter. Compared to other bee types, mining bees are somewhat drab-looking. They range from 0.3 to 0.7 inches long.
From the genus Melissodes, male long-horned bees sport extra-long antennae. These ground-nesters are active in summer and similar in size to mining bees.
Striped sweat bees (genus Halictus), small sweat bees (genus Lasioglossum), and metallic green sweat bees (genus Agapostemon) also nest in-ground. Active in summer, some sweat bee species are so small they’re mistaken for gnats.
Tunneling and Cavity-Nesting Bees
“Most of our other native bees nest in pre-existent tunnels,” Shepherd continued. “That might be in dead tree. . . or it might be in a hollow twig.” Among the tunneling bees? Small carpenter bees (genus Ceratina) are skinny, shiny, and small—just 0.1 to 0.6 inches long.
A couple of tunneling bees—namely the carder bees (genus Anthidium) and the leafcutter bees (genus Megachile) go to great nest-building lengths. Carder bees scrape away plant fibers for use inside their tunnels. And leafcutter bees, equipped with impressive jaws, remove circular leaf sections with which they line their tunnels.
You’re likely already familiar with mason or orchard bees (genus Osmia) which readily accept manmade nest boxes. There are about 130 mason bee species in the U.S.
If you live in the eastern states, you also probably know of the large carpenter bee (genus Xylocopa.) Some of these east-based tunnelers will bore into solid wood—including the walls of our homes! (Fortunately, large carpenter bees don’t seem to have this habit in the West.)
As for the cavity-nesters, there are just under 50 bumble bee species (genus Bombus) in the U.S. These bees are often colorful, velvety, and big—big enough to occupy abandoned mouse holes and similarly sized areas.
How to Help Native Bees
Encouraging more plant diversity is one of the simplest ways to attract and support these varied pollinators. That means allowing some “weedy” areas to thrive and planting many varieties of native perennials. This helps provide more pollen and nectar sources for more kinds of bees.
In fact, research recently published in the journal Proceedings of the Royal Society B showed that the overall numbers of important pollinator species grew along with the numbers of different plant species available. The researchers used mathematical modeling to analyze data from 11 “plant–bee visitation networks” in New Jersey. Rather than considering individual plant species, they looked at mixtures of plant types.
These made up the “whole-plant communities” in an area.
Within whole-plant communities, rare native bees made surprisingly important contributions. “They filled distinct functional roles, in this case pollinating different plant species,” the researchers noted.
Offering more diverse habitat for native bees also counts for a lot. That can be as simple as leaving some small bare patches of ground in your garden. Being a little less zealous with your fall garden cleanup also makes a difference. After all, many kinds of bees will tunnel into hollow or soft-centered stems after plants have begun to die back.
Give them an assist by leaving some broken, hollow stems in place. Alternatively, you can incorporate these stems into small brush piles.
Have any dead or dying trees on your property? Certain native bees also will make their homes in these.