What Do Butterflies Do in Winter

British winters can be difficult enough to cope with for the hardiest of animals, so it seems unfathomable that insects (especially butterflies, with their gossamer-look wings) are able to live through them and survive until the warmer weather of spring.

However, survive they do - and it's wonderful to see these colourful creatures fluttering around again once the frost melts and the first of the flowers emerge.

But what exactly do butterflies do to stay alive during the worst of the snow, wind and rain? Where are they when we don't see them? Here's a little information that should enable you to better understand our butterflies and their habits.


Strategies to get through winter

We often say that butterflies hibernate during the colder months, although this isn't strictly true; actually, they enter a period of dormancy, although the effect of sleeping through winter is the same.

They can do this in several ways: as an egg, larva, chrysalis or in adult form, dependent on species. This isn't simply a random choice or a technique to keep warm, but is a way of ensuring that the insect's awakening in the spring corresponds with the peak availability of its main food source.

Most butterflies lie dormant in larval stage, while pupation is the next most common strategy. Eggs and adults come next in order of commonality, although some species are able to overwinter in more than one form, including the Speckled Wood.

Butterflies like the Large White or the Orange-Tip tend to head to the base of a food plant, the roots of a tussock of grass, or just below the soil's surface to enter the chrysalis stage, while species including the Dingy Skipper, Pearl-Bordered Fritillary and Marsh Fritillary will usually adopt similar tactics, only they'll be in caterpillar form.

The Purple Hairstreak and Essex Skipper are among those that will lay their eggs on vegetation, whereupon a caterpillar forms in each before winter arrives. The eggs will then weather the storm of the colder months before warmer spring weather prompts the eggs to hatch and the caterpillars to start feeding.

Finally, a list including the Brimstone, Comma, Peacock and Small Tortoiseshell lie dormant as adults and seek refuges like sheds, outbuildings, log piles and caves to remain warm and dry enough.


Why do I see butterflies indoors in winter?

Most people will have seen butterflies in their homes during winter months, particularly once the central heating is on. This happens because the insects have become confused about what season it is.

The Small Tortoiseshell and the Peacock begin looking for dry places to seek shelter in the early autumn, when our homes are still typically cool. They mistake our rooms for somewhere suitable to lie dormant and begin to rest.

However, when we turn on the radiators, they assume it is spring and wake up to begin looking for food.

Unfortunately, this can prove fatal because there will be no nectar-filled flowers for them to feast on and so they will waste energy while flying around to search for a way out. Also, if they manage to get outside and end up somewhere damp, they may get fungal infections or simply die from the cold.


What should I do if I find a butterfly in winter?

If at all possible, it's best not to move any butterflies that you find lying dormant and wait for them to awaken in March or April, particularly if you have discovered them in a porch and don't really need to disturb them.

However, this might not always be feasible, plus if they're in a living room and it starts to get warm, they'll probably wake up anyway.

If your butterfly is already moving around, it's best to try to get it calmed down again so it will re-enter dormancy. If you can, catch it in a shoe box with ventilation holes, put the lid on and then put the box in a cool, dark place for an hour or so.

The insect should then become sluggish and slow again, but don't simply put it outside on the garden fence and hope it will find its own place to hide. Instead, carry it somewhere sheltered and dry like a hollow tree or woodshed and gently place it inside.

Better still, gently transfer it to a dedicated insect hibernation box, where it will have the shelter it needs for the rest of the winter and also a means of escape come spring.

In the meantime, while the butterflies sleep peacefully, why not read up on creating a garden that will benefit them next year using one of the helpful books we have in stock?