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From Issue #37 February 27, 2014

To Bee or Not To Bee

A bumblebee species disappears from Vermont. Is it gone forever?

By Madeline Bodin Twitter icon 

Tri-colored bumblebee

Sara Zahendra curses when she sees the parking meter: documenting the disappearance of a species should not involve paid parking.

“Could I submit a parking ticket with my expenses?” asks Kent McFarland, leader of the Vermont Bumblebee Survey, as Zahendra, the survey’s biological technician, scrounges for quarters.

Leif Richardson, a doctoral student at Dartmouth University, has co-written two bumblebee identification guides. On this mid-September day, he quietly tucks collection vials into his pockets while McFarland feeds the meter and Zahendra flits around the car, packing gear and probing the cushions for more quarters.

With two hours on the meter, they don’t head directly into the woods but instead walk toward a retention pond. To find bumblebees, you have to find flowers, and in very late summer there are more flowers in fields than in forests. McFarland, whose favorite bumblebee is Vermont’s showiest, the tri-colored bumblebee, steps over a guardrail and is swallowed up by the tall grass that surrounds the pond. Only his insect net is visible, sticking up over the grass like a periscope.

Zahendra, whose favorite bumblebee is the lemon cuckoo, which she describes as tough with a pretty yellow face, crosses the street and plunges into a field of goldenrod. A battered paper plate is caught in the stalks near the road. Airplanes roar as they lift over the treetops. Sirens from the nearby hospital punctuate the urban hum. It’s not that bumblebees don’t appreciate city life; they can thrive in parks and green spaces. But recently things are tough for them everywhere they flit.

Hive minds

Nearly half of the 46 bumblebee species in the United States are in a dangerous state of decline. As many as 12 of those species may be headed for extinction. The relative abundance of at least four of those species has dropped by 90 percent. These imperiled bees are not disappearing from a faraway rainforest, but from our city parks and our own backyards. They are disappearing from places like the University of Vermont’s Centennial Woods, which has been swallowed up by the city of Burlington, Vermont, and now has metered parking.

The bumblebees’ decline was swift, striking in the late 1990s, but mostly unnoticed, because not all species have declined and, honestly, how many people can tell one species of fat, fuzzy bumblebee from another?

There are several factors working together to cause the bumblebees’ decline, says Richardson. Habitat loss is one of them. It is unlikely that UVM students 50 years ago encountered so many buildings or this much pavement. A well-tended lawn is a wasteland to a bee. The weather extremes associated with climate change are another factor, as are pesticides.1

A less well-documented factor is the presence of honeybees, says Richardson. While bumblebees are native to North America, honeybees are not. Scientists are not sure how or even if honeybees compete with the native bumbles, but they have noticed that where there are a lot of honeybees, there are fewer bumblebees than expected. With that in mind, Colony Collapse Disorder in honeybees might seem like a break for bumblebees. But even with honeybees in sad shape, they still appear to be overwhelming the bumbles.

With barely a twitch, Richardson has a bumblebee in his net. He reaches in and plucks it out. Its body is fuzzy in a bristly sort of way, and warmer than the air, which is warm enough that the three scientists are in T-shirts. The bee vibrates with a mechanical intensity. Richardson knew this was a male bumblebee before it lodged in his net. Males lack a stinger and have seven terga, also known as segments or stripes, while females have six terga plus a sharp, pointy end.

Impatiens,” he says. “We have that.” Bombus impatiens, or common Eastern bumblebee, pollinates tomatoes and other crops in greenhouses. Like honeybees, bumblebees are prodigious pollinators. Unlike honeybees, bumblebees can work in relative cold. Also, since they are native to North America, they are adept at pollinating fellow native plants, like tomatoes and blueberries. Their skill at pollinating crops makes bumblebees economically important, but they are also vital to the lifecycle of native wildflowers, giving them an ecological role that can’t be tallied in dollars and cents.

European bee breeders imported this bumblebee species and others to breed and sell back to American farmers. The imported bees didn’t return alone. Richardson pleads lack of documentation, but says the evidence is good that non-native parasites, particularly a fungus and a gut protozoan native to Europe, infected the re-imported bees. Those parasites spread to wild bees, contributing to the bumblebee decline.

The species of which Richardson holds a specimen is doing fine, however. That has more to do with the fact that this type of bee breeds quickly and builds large colonies than any immunity from the factors harming other species of bumblebees, Richardson says. He lets the bee go, and it disappears like a thought.

Sara Zahendra

Buzz-worthy

Let’s make something clear: the commonly used names of bumblebee species are maddening. American bumblebee, common Eastern bumblebee, half-black bumblebee, yellow bumblebee, tri-colored bumblebee. Aren’t most bumblebees half black?

The American bumblebee sounds like it should be as fundamental as fireworks on the Fourth of July. It once was, but it’s become harder to find after decades of decline. Two orange stripes should make the tri-colored bumblebee distinct, but other bumblebees also have orange on their bodies, including the rusty-patched bumblebee.

The Latin- or Greek-derived scientific names may be somewhat impenetrable to those who never studied the languages. But after a while, they become as good a name as any. The rusty-patched bumblebee, for example, is Bombus affinis, or plain old affinis to its friends. Bombus is the genus name that all Vermont bumblebees share. These scientific monikers are the only ones that McFarland, Zahendra, and Richardson use.

The trio catches dozens of bumblebees, but each one of them is an impatiens. As they walk toward the woods, McFarland guesses that UVM students have found seven species of bumblebees in and around Centennial Woods over the decades. Zahendra counts on her fingers as she names the species in the UVM collection. She says the total is 10, and Richardson agrees. “Well, we have one right now,” McFarland says.

Zahendra spent the last two summers traveling across Vermont to chase bumblebees with a butterfly net as one of two paid technicians who conducted the Vermont Bumblebee Survey along with 30 volunteers. Her prior work had her running after dragonflies and preparing samples of their wings for chemical analysis. Before that, she catalogued butterflies for a comprehensive, five-year survey of Vermont butterflies that resulted in a 300-page report.

The report that results from the bumblebee survey will not be anywhere near that long. Vermont has a possible 17 bumblebee species, compared to 103 for butterflies. McFarland scraped together only two years of funding for the bumblebee survey from private foundations, while in better times the Vermont Fish and Wildlife Department had kicked in most of the five-year butterfly survey’s funding.

Richardson and McFarland hatched the plan for the bumblebee survey together. It took McFarland five years to assemble the money. Now, after two years of using scientific survey methods based on the national Breeding Bird Survey, they haven’t come across a single affinis, or rusty-patched bumblebee, which 30 years before had dominated the University of Vermont’s collection. This mid-September search of Burlington is a last-ditch effort to find bumblebees under the same conditions the students did.

The sting

Strolling along the main trail in Centennial Woods, the group comes across a patch of orange jewelweed, a bright, shade-tolerant succulent also known as spotted touch-me-not. “Let’s do this jewelweed,” says McFarland. He knows that his quarry, affinis, so craves jewelweed nectar that it “nectar robs,” chewing through the side of the flower to get the nectar, since its tongue isn’t long enough to reach inside.

Richardson swings his net. “What did you get?” McFarland asks.

Impatiens,” Richardson replies.

“I think it’s more like impatience,” says Zahendra.

Richardson snags a bumblebee on a Joe Pye weed. “A new species,” he says. “Vagans.” Also known as the half-black bumblebee, it’s one of the most common bumblebee species in the East, but Zahendra and McFarland’s happy shout isn’t entirely sarcastic.

Spotting, let alone catching, an affinis would erase every other disappointment of the day, but the three had agreed before they left the car that finding an affinis in Burlington was impossible. It had just been too long since one had been seen in Vermont. But that doesn’t mean it’s gone from the Earth. Affinis was spotted here and there in the Upper Midwest through the late aughts, although it hasn’t been seen recently. Some bumblebee experts, including Richardson, expect it to turn up somewhere in the Midwest again someday. Bumblebees, all insects really, are like that.

The two-year survey of Vermont’s bumblebees has turned up a surprising number of terricola, or yellow-banded bumblebees, another of the bumblebee species whose numbers have plummeted across the eastern United States in the past 20 years.

Finds like this keep the entomologists who study bumblebees from complete despair. But the statewide survey didn’t uncover a single affinis or pensylvanicus, the American bumblebee.

Also missing in Vermont is Ashton’s cuckoo bumblebee, a species that parasitizes affinis and terricola colonies the way a cuckoo or a cowbird parasitizes the nests of other birds: by laying its own eggs there and tricking the other bird into hatching them and raising the young. When a bumblebee species disappears, the cuckoo bumblebee that depends on it disappears too.

In early 2013, the Xerces Society, an international conservation organization for insects and other invertebrates, filed a petition to have affinis listed as endangered under the federal Endangered Species Act. McFarland knew the group was still waiting to hear from the US Fish and Wildlife Service about the federal listing, even as he walked through Centennial Woods, planning his report to list affinis as an endangered species in Vermont.

Affinis was listed as an endangered species in Canada in 2012. In Connecticut in 2010, affinis, ashtoni, and terricola were listed as species of special concern, a designation that is just below the category of “threatened.” Six other states have some form of legal recognition for the plight of affinis in the works, says Sarina Jepsen, endangered species director for the Xerces Society.

Be hopeful

McFarland, Zahendra, and Richardson reach a wet meadow, the point in Centennial Woods that is the farthest from the entrance. With the meter ticking, the fastest way back to the car is the way they came in, which means seeing the same habitats, and therefore roughly the same bees, again. “I wish I would have put three hours into the meter,” McFarland says.

McFarland and Zahendra use the walk back as an opportunity to ask Richardson, whose reputation as a bumblebee expert is growing nationally, some of the questions that have come up in two years of studying bumblebees nearly full time. “Do bumblebee males die right after they mate?” Zahendra asks. Like honeybee males, a bumblebee male’s only role in a colony is to mate with a queen.

“No,” says Richardson. “We don’t know how long they live, though. This is one of those things where you’d think we would know something about it, but we don’t.” It turns out there are a lot of things Richardson and other bumblebee experts would like to know about bumblebees, even basic things, but don’t.

Bumblebees have always escaped us. So few can tell the difference between a tough, pretty-faced lemon cuckoo bumblebee and a showy tri-colored bumblebee, so how could we know when they are gone? How can we miss them? They are disappearing before we have given them a thought.

Richardson’s favorite bumblebee is terricola. It’s one of the handful of bumblebee species that have been in the swiftest decline in the East. It’s also the species that turned up in surprising numbers in a careful two-year search of Vermont. Because there is a chance it may be recovering, McFarland plans to request that it be listed as threatened, not endangered, in Vermont. That’s one rung down on the ladder of doom and something very much like hope.

Tri-colored bumblebee by Kent McFarland. Sara Zahendra by the author.


  1. See “Bumbling Idiots,” in Issue 23 (Aug. 15, 2013), by Chris Stokel-Walker. 

Vermont-based writer Madeline Bodin writes about our relationship with the natural world, including articles about the wood in baseball bats and the resurrection of a butterfly species, for publications such as the Boston Globe, Discover, Wildflower, and Woodland.

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