Bees, wasps and butterflies in winter

Purple hairstreak egg (c) Peter Eeles

Overwintering strategies are vital to creatures which depend on pollen and nectar for their food or those which prey on such species.

Unlike honey bees, most bees and wasps perish before the winter sets in – the only survivors are young, mated queens.

Bumblebees spend the winter in a dormant state, having gorged on nectar and pollen to build up fat reserves and retired alone to an underground nest below the reach of frost. In the spring the young queen lays her first eggs which will all hatch female workers to rebuild the colony.

Buff tailed bumblebee

Buff tailed bumblebee (c) Richard Burkmar

With winters becoming warmer, however, buff-tailed bumblebees have been recorded in active colonies through the cold season, feeding on winter garden flowers such as Mahonia and Viburnum, and recently tree bumblebees and early bumblebees are following suit. Add some winter-flowering plants in your garden and watch out!

Some solitary bees overwinter as dormant new adults still in their cocoons (tawny mining bees, ashy mining bees and red mason bees), having grown from egg to adult during the summer.

Others – leafcutter bees, wool carer bees and yellow-faced bees – grow from egg to larva during summer and overwinter in torpor, pupating in the spring. As many of these bees overwinter in their nest site, leaving dead hollow stems such as bramble in your garden or hedges rather than cutting them down in autumn can make a real difference to the winter survival of these species.

Queen wasp

Queen wasp (c) Nick Upton/2020Vision

Adult wasps feed on sugary liquid secreted by their larvae, which themselves are fed on insects and carrion. In late summer, when the larvae have matured, wasps turn to feeding on nectar and other sweet substances. As these resources disappear with the onset of winter most of the wasps perish, leaving only the young queens to overwinter. These are the ones you might find in your curtains, where they tuck themselves up in tight bundles and shut down into dormancy.

Do try to keep disturbance to a minimum around your garden to give all these creatures a chance to get through the winter!

Of our 57 resident butterfly species, 31 spend winter as a caterpillar, 11 as a chrysalis, 9 as an egg and 5 as adults. Speckled woods alone overwinter in one of two stages, either as caterpillar or chrysalis. 

Butterflies are the embodiment of summer, but odd ones can be spotted on warm days late in autumn or early in spring. These are the five species that hibernate as adults – brimstones, peacocks, small tortoiseshells, commas and red admirals.

Red admiral

Red Admiral (c) Guy Edwardes/2020VISION

Red admirals are also strongly migratory, and only recently have taken to hibernation - most still depart south in late autumn after feeding on fallen apples and ivy flowers. The other four hibernators seek out somewhere safe and insulated to sleep through the coldest months in a fairly constant temperature, relying on their ‘dead leaf’ camouflage to avoid predation. Garden sheds, attics and cellars offer suitable places, or beneath tree bark and in tree holes. Small tortoiseshells are the only species to regularly overwinter in houses.

Large white pupa

Large white pupa

The white butterflies (large, small, green-veined and orange tip), holly blues and green hairstreaks – all overwinter as a chrysalis (pupa), which survive in folds in tree bark, attached to twigs or on walls or fences. Camouflage is vital to avoid the attention of hungry birds and mice.

All the brown butterflies and fritillaries spend winter as caterpillars. They enter diapause – a period of suspended development - hidden away in clumps of dead leaves or grass tussocks as small caterpillars, re-emerging in spring to feed and grow. Common blues and small coppers adopt the same strategy. A large proportion of the species overwintering as caterpillars are meadow and grassland species, so you can really help them to survive by leaving some uncut grass to shelter them.

Purple hairstreak egg

Purple hairstreak egg (c) Peter Eeles

Purple hairstreaks, brown hairstreaks and silver studded blues are among the species which winter as eggs, each attached to a twig of the appropriate food plant so that when the egg hatches in spring there is a ready food supply for the very hungry caterpillar.

The order in which we see butterflies flying in the spring depends on how the species overwinters. Those who survived as dormant adults are the first in flight, but others will soon follow as the season warms and our countryside comes alive again.