By Amanda Shalit, NCF Seasonal Botany/Ecology Field Assistant
If you take a walk at Windswept Bog while the roses and irises are blooming or venture out to Head of the Plains while the bearberry and blueberries are in flower, chances are you’ll be greeted with the delightful hum of bees! You can find bees busying themselves around plant nurseries or visiting window boxes along Main Street. Bees have become all the buzz lately, but the conversation rarely strays beyond honeybees. Honeybees are charismatic little creatures, valued for their pollination services and honey production, but they’re a non-native bee, considered livestock.
Native bees are the true unsung heroes! In addition to bumble bees and carpenter bees, the most well-known native bees, there are also thousands of species of other native bees, including squash bees, sweat bees, digger bees, mason bees, leafcutter bees, and carder bees. Whew! There are over 20,000 known bee species in the world, 4,000 of which are native to the United States.
This diversity of native bees is important in healthy ecosystem functioning. Native bees are estimated to pollinate around 80% of flowering plants around the world.
Some are intimately tied with a particular plant; one cannot survive without the other. Additionally, many native bees easily pollinate plants that honeybees cannot, such as tomatoes and squash. These plants require bumble bees and squash bees respectively in order to be successfully fertilized. If you’ve ever enjoyed tomatoes, squash, blueberries, cherries, or cranberries, make sure to thank your native bees!
Spotlight on Bumble Bees
Bumble bees are particularly well-known members of the native bee cohort, and for good reason. As they fly from flower to flower, collecting pollen and sipping nectar, bumble bees carry pollen grains in their characteristic fuzz, facilitating cross-pollination needed for successful plant reproduction. Additionally, bumble bees have a special method of pollinating called “buzz pollination,” which is what allows them to pollinate tomato plants when other bees can’t. In this distinctive maneuver, the bumble bees grab onto a flower and vibrate their abdominal muscles, creating a characteristic buzzing noise and shaking free a huge pollen load. Additionally, this ability to vibrate their flight muscles allows bumble bees to warm themselves, despite being cold-blooded, as all insects are. This warming ability allows bumble bees to pollinate at lower temperatures, lower light levels, and in wet, windy conditions that have most honeybees shivering in their hives. Historically, Massachusetts was home to twelve species of bumble bees, but two are now considered extirpated from the state.
The most common bumble bee species I’ve observed on Nantucket are the common eastern bumble bee (Bombus impatiens), the two-spotted bumble bee (B. bimaculatus), and the brown-belted bumble bee (B. griseocollis). I’ve also seen less commonly the half-black bumble bee (B. vagans), the confusing bumble bee (B. perplexus), as well as one golden northern bumble bee (B. fervidus).
Bumble Bees and the Hive Life
These big, fuzzy bees are “eusocial”, meaning they have a similar caste system to honeybees where there is one queen and many workers. However, the life cycle of a bumble bee nest is unlike that of a honeybee colony. Whereas honeybee hives remain active through the winter, albeit in a diminished state, bumble bee nests are annual, never lasting more than one growing season. A bumble bee nest at the peak of summer is a well-oiled machine. The queen remains in the nest, laying eggs, while workers rear larvae, leave the nest to forage for food, care for young, and complete other tasks around the nest. That means that by this time of year, every bumble bee you might spot is likely a female worker bee, out foraging to support a new brood of workers.
This remains true until the end of the summer, when queens begin laying eggs that develop into male bees. That’s right, no sex reveal party necessary; bumble bee queens can choose to lay either fertilized eggs that become females, or unfertilized eggs that become males. The male bees are the season’s most (and only) eligible bachelors, often seen hanging out on flower heads while they wait for future queens to fly past. The future queens mate with one or several males, then forage in order to gather enough food for themselves to overwinter. These tenacious bees overwinter alone underground, hibernating in abandoned rodent burrows, under leaf litter, inside tree hollows, or in other small cavities.
When they emerge in the spring, the cycle starts anew. A new queen will emerge and begin to forage, simultaneously searching for a nesting site in similar places to where she overwintered. In the spring, they emerge and begin foraging and searching for a place to establish their nest. Bumble bees do not dig or build nests the way carpenter bees, digger bees, or miner bees do. They simply find pre-existing cavities in which to establish their nest for the growing season. Once she has gathered enough food, she remains inside the nest to lay and brood her first batch of eggs, which will become her first daughter worker bees.
Bumble bee nests are notoriously hard to find since they’re often underground and well-hidden, but not impossible! Since being on Nantucket, I’ve found not one but three bumble bee nests. One, out at Head of the Plains, is home to two-spotted bumble bees, while two others, hidden in cranberry bogs at Windswept Bog, belong to two-spotted and brown-belted bumble bees respectively. Nests at their peak can house 50-500 bees, depending on species and habitat. It’s uncharacteristic for bumble bees to be seen flying close to the ground among taller vegetation, and even less usual for bees to be seen flying in and out of holes in the dirt, so this behavior can be a sign that you’ve found a nest!
Humans and Bees
So, how do humans interact with bumble bees? Do they make honey? Good questions. The answer is… yes, but no, not like that. Bumble bees do store nectar, the main ingredient of honey, but they don’t make honey in the same way as honeybees. They don’t store honey in that infamous honeycomb pattern, and since bumble bee colonies are annual, they do not store honey in the same mass quantities as honeybees.
Do they sting? While male bumble bees do not have the ability to sting (they in fact lack a stinger entirely), female bumble bees do have this ability. However, whereas the barbed stinger of a honeybee sticks in the skin and unfortunately kills the bee when it rips out, bumble bees have smooth stingers, meaning they can sting multiple times. Fortunately, bumble bees are incredibly docile in nature. I’ve had the incredible experience of holding several wild bumble bees, none of which have caused me any harm. Unless you’re trying to catch or kill bees, or poke around in their nests, it’s likely that these little workers will leave you be.
How can I help?
Native bees, including bumble bees, are in decline. The best way for people to help native bees is to plant pollinator gardens, focusing on planting flowers native to your area that will provide nutritious pollen and nectar for bees, moths, butterflies, and other pollinators. For more info on how to get started on this kind of project, check out this MA.gov website on pollinators.
About the Blog Post Author:
Amanda Shalit, one of this season’s NCF Botany and Ecology Field Assistants, is originally from the suburbs of Chicago, and spent the last four years at the University of Wisconsin – Madison, where she graduated with a degree in botany, conservation biology, and environmental studies. Most of Amanda’s previous field work centered around tallgrass prairies across Wisconsin, but she has ventured into researching plants in the tropics and tundra too. The last two summers found Amanda working on a research project focused on wildflower pollen quality and bumble bee foraging patterns. This season, she has been excited to work with NCF on Nantucket, learning an entirely new flora and fauna, and assisting with a varied slate of botany and ecology field research. Her eye for bumble bees has so far led to the submission of several records to the Bumblebee Watch website–the first records for Nantucket on that site, which documents Bumble Bees around North America–and to iNaturalist, a widely used platform for recording natural history finds of all kinds.