Miner bees cover for honey bees in pollination chores
By Morgan Simmon, The Repulic July 8, 2011
TOWNSEND, Tenn. – The family from Missouri couldn’t believe what they were seeing. Here was a park ranger crouched next to one of the historic structures in Cades Cove, enveloped by a cloud of bees.
And, he was beckoning them to come over.
“Come here, trust me,” said ranger Mike Maslona. “You’re going to get closer to bees than you’ve ever been in your life.”
Beneath the building was a large colony of miner bees, also known as chimney bees or mining bees. As the name suggests, miner bees dig elaborate nests in dry, well-drained soil — the kind of dirt found beneath many of the cantilevered barns and old houses in the Great Smoky Mountains National Park.
Maslona explained that miner bees belong to a group of ground-nesting bees that do not make honey and do not sting. Resembling small bumblebees, the miner bees went about their business while the family from Missouri — Jeff Carnell and his 6-year-old son, Seth, and 4-year-old daughter, Clara — marveled at the decibel level of the swarm buzzing around their heads.
“I want you to listen,” said Maslona. “They’re talking to you.”
Miner bees are found across much of the eastern U.S. In the park, the adults emerge in early summer and live just a few short weeks as they work feverishly to construct their tunnels and egg chambers. The females stock the egg chambers with pollen as food for the larvae. The larvae transform into adults over the summer, but remain in the burrow over the winter before emerging in spring or summer to restart the cycle.
Adriean Mayor, museum curator for the Smokies’ Twin Creeks Science and Education Center, said miner bees are native to the U.S. and able to resist colony collapse, a disorder that has plagued imported honeybees in recent years.
“They’re solitary in the sense they don’t form hives, but when they find the right soil, they can be found nesting in large numbers next to each other,” Mayor said. “All our native bees … play a big role as pollinators, especially with the decline of honeybees.”
The miner bees’ gentle nature is characteristic of native bees in general, Mayor said. “People tend to think of bees as being aggressive, but most native pollinators are very docile. They’re basically just minding their own business.”
During the 1970s, scientists began detecting an alarming drop in native bees across North America. According to the Xerces Society, a nonprofit organization that specializes in pollinator conservation, native bees pollinate one-third of the planet’s food crops, but are facing multiple threats from sources like pesticides and habitat destruction.
Approximately 15 bumblebee species live in the Smokies. One, the rustypatched bumblebee (Bombus affinis), hasn’t been seen in the park since 2000. Another park species, the yellow-banded bumblebee (Bombus terricola), also has become scarce. Biologists suspect these and other wild bumblebees in the U.S. might be suffering from an exotic disease spread by bumblebees brought from overseas to pollinate hothouse tomatoes.
After repeated assurances from ranger Maslona that the bees wouldn’t sting, Ezequiel Magana of Little Elm, Texas, knelt near the nest site beneath the building and stared transfixed as the bees flew in and out of the small holes at the entrance to their tunnels.
Nearby was a stream where the females collected water to regurgitate beneath the building to soften the clay. In terms of materials and engineering, the miner bee nests called to mind the mud-gourd nests of cliff swallows, or perhaps the adobe cliff dwelling of the Anasazi Indians in Mesa Verde, Colo.
“There are bees to stay away from, and bees to shake hands with,” said Maslona.
“They better not have nested in my nostrils,” said Magana as he walked back to his car.