Honeybees get all the press, but the fascinating story of North America’s native bees — endangered species essential to our ecosystems and food supplies — is just as crucial. Through interviews with farmers, gardeners, scientists, and bee experts, Our Native Bees (Timber Press), by Paige Embry, explores the importance of native bees and focuses on why they play a key role in gardening and agriculture. The people and stories are compelling: Paige Embry goes on a bee hunt with the world expert on the likely extinct Franklin’s bumble bee, raises blue orchard bees in her refrigerator, and learns about an organization that turns the out-of-play areas in golf courses into pollinator habitats. Our Native Bees is a fascinating, must-read for fans of natural history and science and anyone curious about bees.
The following excerpt comes from the section Bees, Blueberries, Budworms, and Pesticides.
Many species of Andrena are common out in the blueberry fields. They are called mining bees and get that name from their method of nesting. Back in the 1970s, Martha Schrader and Wallace LaBerge studied Andrena bees in lowbush blueberry fields in Maine and New Brunswick. They wrote a description of Andrena regularis starting a nest. The bee flies up loaded with pollen, but for some reason she has not already set up her nest, so she begins digging. Dissatisfied, she soon quits and starts a new hole.
For whatever reason the second spot is better than the first, and she digs vigorously, shoving bits of dirt out from underneath her body. She crunches the larger clumps of soil into submission with her mandibles. Pretty soon she is out of sight down the hole, with bits of dirt occasionally getting ejected from the entrance. After about 20 minutes she comes out, flies a zigzag orienting flight, and then zips back into her hole to dig some more. Andrena bees are called miners for a reason.
Real mining bees
Ground nesting is the norm among bees, with about 70 percent setting up their household somewhere underground. Some may use preexisting holes such as old rodent holes; others excavate their own. How bees set up their nest cells varies. Some place the cells around the main tunnel like the spokes on a wheel, while others have cells that are seemingly randomly arranged in side tunnels. Some burrow deep, and others stay close to the surface. The species that Schrader and LaBerge studied dug out its nests to what seems like a rather paltry depth of six to seven inches, but an Andrena regularis is only about half an inch long. That bee was digging a tunnel twelve to fifteen body lengths deep. That’s like a six-foot-tall man digging a tunnel that’s 72 to 90 feet deep. From a bee’s point of view, these really are mine shafts. In other areas these bees have done deep mining, digging down to a whopping depth of eighteen inches.
Andrena bees often nest in aggregations, sometimes with the nest entrances exceedingly close together. One aggregation in an abandoned blueberry field in New Brunswick had 36 nest entrances in a four foot by three foot area. Some of the entrance holes were only an inch apart. These miners may be solitary bees, but they certainly don’t mind being close to their neighbors. They aren’t exactly apartment dwellers since they all have their own front door; it’s more like living in townhomes.
Some species of Andrena do live like apartment dwellers. These are the communal nesters, where up to a few dozen bees share one front door. Once in the ground, each bee digs her own side tunnel and provisions her own nest. One nest of Andrena crataegi in Maine had 44 females using the same nest entrance. Apparently, the morning exodus was orderly, with the bees leaving one to two minutes apart and no Keystone Kops moments of two bees trying to get out at once.
Andrena species are common visitors to wild blueberries all over Maine and southeastern Canada. 31 different species have been found visiting blueberries in Maine. When the fenitrothion rained down in New Brunswick, Andrena took a hit, and they weren’t alone.
A sniff test for Andrena?
Telling one Andrena species from another is notoriously difficult for beginners. Even recognizing that a bee is some sort of Andrena can be difficult. I thought I might have found a fun identifier when I ran across a paper entitled, “Comparative Analyses of Lemon-Smelling Secretions from Heads of Andrena F. (Hymenoptera, Apoidea).” Lemon-fresh bees? Regretfully, lemons aren’t the only thing Andrena bees may smell like. Robbin Thorp mentions two other groups of smells: a musky oniony odor and a flowery sweet one. Some other bees have fragrances as well, so I’ve given up on the idea of using an easy sniff test for Andrena.
Excerpted from Our Native Bees by Paige Embry. Used with permission from Timber Press.