Bumble bees are culturally iconic and essential to our environment. While unwittingly inspiring classical music, soft toys, and jewelry, bumble bees pollinate flowers both obscure and important to human food systems. The most ubiquitous of the 18 bumble bee species encountered in the northeastern United States and eastern Canada is, appropriately, the common eastern bumble bee (Bombus impatiens).
This species is relatively easy to identify. Starting from the front, this bee’s colors are black, yellow, and back to black. The head is entirely black. The thorax (where wings and legs attach) viewed from above is covered in yellow hairs, frequently with thinning hair between the wings, revealing its black exoskeleton. Yellow hairs extend back to the first abdominal segment, and the rear segments are black. These bees range in size from 1/3 of an inch in the case of worker bees to ¾ of an inch or more for the largest queens. Male bees, or drones, measure in the middle of that size range and can be distinguished by a forward-pointing tuft of yellow hair on the face. (The two-spotted bumble bee, Bombus bimaculatus, is similar in appearance, but its yellow hair extends to the center of the second abdominal segment, leaving room for black spots left and right. This species is less common and is not often seen after August.)
Common bumble bee populations peak in September, and these bees actively forage through October and into November. Unlike honey bees, which overwinter as a group in a hive or tree cavity, bumble bee workers die in late fall, and only mated queens overwinter. In late autumn, a queen bee finds a sheltered spot to hibernate. Favorite locations include abandoned mouse and vole burrows as well as holes and voids beneath rocks and fallen forest debris. Bumble bee queens’ adaptations to survive the cold include glycerol in their hemolymph (the insect equivalent of blood), which serves as antifreeze, protecting the bee’s cells from damage during below-freezing temperatures.
In spring, as temperatures warm, queen bumble bees emerge to seek nutritious pollen and nectar from early blooming plants – and a place to establish the year’s brood. Queens tunnel into soil to make chambers or move into existing holes. Within her chamber, a queen will build a wax honey pot and fill this with regurgitated nectar to sustain herself between brief foraging trips. She also deposits pollen onto the chamber floor. After laying her eggs on this pollen, the queen continues to forage and provides her hatchling larvae with both pollen and nectar. She keeps the eggs and young larvae warm by flexing her flight muscles to generate heat. Over the course of a month, these larvae grow, pupate, and emerge as adult worker bees, all of them female. The workers take over foraging to feed both the queen and larvae, allowing the queen to focus on laying more eggs.
Worker bees live for a mere two weeks. During that time, they consume nectar for their own needs, collect nectar for their queen, and gather pollen and deliver it to the nest to feed larvae. It may seem counterintuitive that active pollen consumers also serve as pollinators, but flowers produce more pollen than bumble bees can eat, and the bees move more than enough pollen to earn their keep. Moreover, bumble bees are on the short list of insects capable of “buzz pollination,” which is the only way eggplants, blueberries, cranberries, and some other plants can be pollinated. The anthers of these species hold pollen in tubelike structures with small openings that keep insects from entering but allow pollen to exit. A bumble bee landing on such a flower uses its flight muscles to vibrate the flower. The vibrations release pollen, which worker bees collect in corbiculae: concave, hairless areas on bees’ tibias designed to hold pollen. Pollen also sticks to the hairs of a bee’s body, and some of this rubs off on other flowers as the bee forages.
Honey bees are incapable of buzz pollination, so bumble bees are essential for pollinating a variety of crops and wild plants, including those grown in large commercial greenhouses that are inaccessible to wild pollinators. Commercial growers build hives that look like large cardboard shoe boxes. Each hive includes a queen, worker bees, and a brood of eggs and larvae. Growers place these hives in shady spots within greenhouses and open the flight door. The queen reproduces, worker bees forage within the greenhouse, and in the process, they pollinate valuable crops.
Whether in greenhouses or in the wild, a queen’s egg laying increases throughout the season, and the colony grows to peak size in late summer or early fall when, instead of worker bees, the colony begins producing queens and drones (male bees) that emerge for their nuptial flight. The transition from yielding only female workers to producing both queens and drones is called the “switch point” and is governed by weather and food supply. In spring, queens lay fertilized eggs using sperm stored from the previous fall. These fertilized eggs all become female worker bees. After the switch point, a queen begins laying some unfertilized eggs that produce drones. At the same time, female larvae hatching from fertilized eggs after the switch point are fed more, mature to a larger size, and become queens.
Emerging males establish territories to attract emerging queens. Ideal territories are close to bumble bee nests and should have abundant flowers both to feed the drones and also to attract queens. The drones scent mark stems, leaves, and flowers with pheromones to attract queens. These emerging queens mate in late fall, then overwinter and establish new colonies the following spring.
According to a 2025 paper by zoologist Tara Cornelisse of the nonprofit conservation organization NatureServe and her colleagues, more than one-third of North American bee species are at elevated risk of extinction due to causes that include climate change, shifting agricultural practices, pollution, and urban development. If you see a bumble bee buzzing around late-blooming flowers this fall, it is likely a drone foraging for nectar or a young queen building up fat as a reserve for hibernation. Come spring, you may be able to help these important pollinators – common eastern bumble bees and others – by converting your lawn to a meadow and eliminating the use of pesticides. If you do retire (or restrict) your lawn mowing, you’ll save time, money, carbon emissions – and maybe a few bees.