Where do bees go in the winter?

A significant number of temperate insects survive these harsh months with some truly radical behavior

A worker bumble bee climbs the roots of an alpine plant to warm her body

Above: Bumble bees evolved in the ancient Himalayas during a period of global cooling. They are one of the only types of insects that can warm their bodies in cold conditions, which they do by unhinging their wings from their flight muscles and shivering their bodies. Here, a worker bumble bee has climbed into the roots of an alpine plant to warm her body during a sleet storm at 9,000 feet in Montana’s Bridger Range.

Have you ever wondered where bees, butterflies, and other insects go during the winter months? We expect to see them flying among the flowers and scuttling across the forest floor during the spring, summer, and even into the fall. However, once the temps drop and snowflakes begin to fall, it’s easy to assume that these creatures have simply disappeared. And while many do vanish—from our view that is—a significant number of temperate species survive these harsh months by harnessing some truly radical behavior. 

A forest bumble bee visits brightly colored wildflowers at 10,000 feet

Bumble bees’ ability to withstand cold temperatures allows them to survive winters in harsh places like Wyoming’s Beartooth Range where snow storms are common even in mid-summer. Here, a forest bumble bee (Bombus sylvicola) visits wildflowers at 10,000 feet.

For example, let’s take our old friends, the bumble bees. Nothing says peak summer to me more than the buzz of one of these fat and fuzzy pollinators. In fact, these insects’ rotund bodies and gentle temperament certainly contribute to their A-List (Bee-list?) status. But these attributes aren’t just for style: they are critical to their survival.

Bumble bees evolved some 25 million to 40 million years ago in the ancient Himalayas during a period of global cooling. Early bumble bees, which lived near Mount Everest, were more wasp-like in appearance. However, as the climate cooled, they evolved thicker hair and larger bodies to preserve warmth. They also developed the ability to unhinge their wings from their flight muscles, allowing the bees to shiver their bodies to increase body warmth. In fact, bumble bees are one of the only kinds of insects that can help regulate their own body temperatures. Most other insects must rely solely on the sun's warmth to do this. As a result, it isn't uncommon to see bumble bees flying when there is snow on the ground, even in alpine habitats on high-mountain peaks. There is even a species of these resourceful insects known as the alpine bumble bee (Bombus polaris), which lives above the Arctic Circle.

At the end of summer, new bumble bee queens emerge and mate. These queens, known as gynes, pig out on pollen and nectar until autumn temps become too cold for flowers to survive and for the bees to forage consistently. At this point, the queens seek out a north-facing slope (which remains cooler) and dig themselves a small hole in the ground, often among tree roots. This is the only time that a bumble bee digs. After she has chosen her overwintering site, the queen will construct herself a small wax cup, which she fills with nectar—a key tool in her survival kit. As winter sets in, the ground begins to freeze and, in many places, snow and ice will cover her burrow. However, within the soil, her body may remain warm enough to prevent her from entering a state of hibernation (brumation is the term for insects). Without food, she would lose weight too quickly and die from starvation. The erratic nature of a warming climate can result in overwintering bumble bees waking too often to sustain their body weight during the months when they are unable to leave the burrow and forage, leading to death before spring and flowers have returned.

Endangered western bumble bee queens (Bombus occidentalis) require freezing temps to survive their winter rest period. Like bears, if their metabolism increases too much, they will prematurely burn off their winter fat stores that allow them to survive the coldest months of the year. (Controlled condition.)

Over winter's long months of torpor—an extended state of inactivity similar to hibernation—the queens' bodies freeze almost entirely solid. However, the insects have another trick in their bag that allows them to survive this extreme cold: a substance called glycol. Glycol is an anti-freeze that keeps the bee's hemolymph (an insect's "blood") from freezing and forming ice crystals, which would destroy its bodily tissues. Other animals in cold-prone places, including some butterflies and even the wood frog, an amazing amphibian, have also evolved to produce glycol. Once the winter months have passed, and the snow has begun to melt, the queen bumble bee will slowly begin moving her legs and body until she can activate her flight muscles, warming herself to the point where she can emerge and feed from the spring flowers that await her arrival. After regaining her strength, she'll begin searching for an abandoned rodent burrow or a good clump of grass in which she'll lay her eggs and raise her young.

Learn more about how WWF is helping to protect pollinators by reducing pesticides.