So, where do insects go in winter?  .. Well, most of them stay here! 

Being cold-blooded means that insects need a range of strategies to continue the species into the next year.  There are basically two ways to do this - migrate to a warmer climate or endure the cold.

Silver Y moths have the right idea! Throughout August and September they return to their winter breeding grounds in the Mediterranean basin, their numbers swelled by individuals that bred here during summer.  However, most insects you see throughout spring, summer and autumn will still be around in one form or another - tucked away in microhabitats such as leaf litter, dead vegetation, under tree bark, in log and stone piles, cracks, crevices, and in sheds, outbuildings and in domestic dwellings – all places that provide insulation and help to reduce the risk of being eaten.

Relatively few species overwinter as adults and most spend the colder months in the egg, larval or pupal stages, in a state of genetically programmed arrested development.

Some insects have ‘anti-freeze’ - cryoprotectant compounds consisting of glycerol, proteins and sugars  - which allow body fluids to remain liquid at temperatures below their normal freezing points.  This enables them to withstand brief snaps of extreme cold, but can’t always protect against prolonged cold periods. Emptying the gut of waste fluids that would otherwise attract the formation of ice crystals is an additional survival strategy.   

Adult insects that die off before winter, such as grasshoppers and crickets, will have already mated and deposited eggs in soil, tree bark or in plant stems during the warmer months. Colonies of wasps and bumblebees also tend to die off before winter, leaving only a young mated ‘queen’ to hibernate until next spring.

Most British butterfly species spend the winter as caterpillars, but adult Brimstone, Comma, Peacock, Small Tortoiseshell and Red Admiral can enter a dormant state, becoming temporarily active on sunny winter days. Individuals that have chosen to shelter in a quiet corner of your home may wake up when the heating comes on, in which case gently relocate it to a cool place such as a shed or outbuilding.

Ladybirds overwinter as adults, and congregate in groups to shelter under bark, in dead vegetation, around window frames, and in greenhouses, sheds and compost bins. You may also find adult shieldbugs in leaf litter or low vegetation such as grass tussocks, sporting their brown-bronze winter camouflage.  Avoid using a leaf blower if you want them to survive into next summer’s breeding season! 

Certain species of dragonfly can spend up to 95% of their lives in the egg or larval stages, living in submerged pond vegetation, in sediment or fast-flowing watercourses that are unlikely to freeze.   Some can take two years to develop so will experience at least one winter underwater, the carnivorous larvae feeding on other aquatic invertebrates.

Many ‘ground beetles’ reduce their activity levels to conserve energy, but continue to feed on smaller invertebrates. Insects that burrow underground, that feed upon decaying organic matter, fungi or bacteria, can potentially eat quite well throughout winter and may benefit from the accelerated decomposition of leaf litter and other organic debris caused by damp conditions. 

Insects that overwinter as adults need to acquire sufficient energy to sustain them for several weeks, so autumn can be a hectic time as they acquire extra calories.  Late-flowering garden plants such as winter heather, ivy and mahonia are excellent food sources when there is little else available, and you may have recently noticed an abundance of hoverflies, feasting on the last remnants of nectar and pollen.

So, when you’re tidying your garden - cutting back foliage or clearing leaves – or digging the soil, building a bonfire, or putting logs on your wood burner, check for signs of life and gently relocate the insect to a safe place if necessary.

The insects that keep your garden healthy are depending on you this winter!