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What do bees do in the winter?

Early Bumblebee ©Jon Hawkins/Surrey Hills Photography

The familiar sight of bees buzzing around and feeding on flowers disappears from view in the winter. But what do they do? And where do they go in the winter months? Bee expert Ryan Clark investigates.

As the nights draw in, the leaves fall from the trees and it gets colder, many of our insects begin to shut down for the winter. The sound of bees is a sure sign of spring and summer, but what are these bees doing now over the autumn and winter?

What do bumblebees do in autumn and winter?

The cycle of a bumblebee colony is usually at an end now, the workers have busily foraged to enable a new generation to be produced with the focus of the colony being switched to producing queen and worker bees. The queens and males mate with bumblebees from another colony, laying eggs the following spring. The males then have done their duty and passed on their genes to the next generation, but these male bees are short lived and do not survive the winter.

After mating, the impressively large queen bumblebees gorge up on nectar and pollen in the nest, where they are safe from predators. The queen then finds a suitable place to overwinter (often underground), ready to wake up in the spring and start the cycle again. The queen bee is the only bumblebee that survives through the year to do this – all the male bees and worker bees die off. Cold, dry places are the best places for queens to overwinter, where they are less likely to wake up early or get attacked by fungi. Around half of these queen bees survive the winter, relying on their fat reserves to keep them alive.

Garden Bumblebee

Garden Bumblebee ©Chris Lawrence

However, in some towns and warmer areas of Britain, people have noticed changes to the bumblebee life cycle, possibly in response to our changing climate. Some bumblebee queens, especially those of the buff-tailed bumblebee (Bombus terrestris) are starting colonies which overwinter instead of all dying off. Instead of hibernating over winter, they start nesting in October or November and produce workers which forage on some of our native plants that are increasingly flowering over winter. Non-native garden plants which flower over winter seem to be important and allow them to forage overwinter. Winter flowering heathers, mahonia, honeysuckle and rhododendron seem particularly popular. These nests produce a new generation of queens and males in February. With warming climates, this phenomenon is becoming more common in cities further north. More information can be found about winter active bumblebees on the Bees, Wasps and Ants Recording Society website where you can submit records of winter active bumblebees.

 

White-tailed Bumblebee

White-tailed Bumblebee ©Penny Frith

What do solitary bees do in autumn and winter?

The majority of bees in Britain are solitary bees though, so what happens to those at this time of year? Solitary bees are diverse and so are their overwintering habits. Most solitary bees have an annual life cycle, with the female gathering pollen and nectar for the nest where they lay their eggs. They then seal the nest which contains their eggs, and pollen and nectar for young bees to eat in order to develop into adults. During the winter months the eggs become larvae and eventually turn into young bees. The lifespan for most adult flying solitary bees is very short, lasting for a few weeks to a month, and this means they never get to see their young. 

Spring flying solitary bee species want to be able to emerge as soon as possible in spring to take advantage of the short flowering times of some early-flowering plant species like coltsfoot and hawthorn. These species develop into adults over the summer, long after their parents have stopped flying. These then overwinter as adults within a cocoon, ready to emerge in spring. Species that fly later in the year overwinter as larvae and develop into adults over the spring, emerging as adults in late spring or summer. As the spring flying solitary bees overwinter as adults, they are sensitive to disturbance, so can occasionally be seen out of season when their nests are accidentally dug up and disturbed.

But some species of bee behave differently…

The females of some species of furrow bees in the south, mate in the autumn when males are present, can overwinter as adults from the previous year and can start nests, producing more females which forage and help more females and males to be produced. Whereas in the north the same species has a cycle of a more typical solitary bee species, with all adults dying off from one year to the next. The small carpenter bee (Ceratina cyanea) is found in the south east of England and is unique among British bees as both the males and females overwinter, usually in bramble stems. 

So when you are enjoying walks in the countryside or working in the garden this autumn and winter, think of the millions of bees and their eggs and larvae all around you surviving the winter in underground nests, hollow plant stems and other cold and dry places, ready to start flying again next year with their familiar buzz and bright stripy bodies.

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