In winter it is logical that we see fewer insects in our gardens. Being cold-blooded, they need the warmth of the sun to stir them into action but you can guarantee that on a warm day, even in the middle of winter, there will be insects around and sometimes plenty of them.
Insects seem so fragile with delicate wings and such small bodies it is incredible to think that they can survive the cold of a British winter but many do.
To cope with freezing conditions many insects change their biochemistry during autumn. In particular they create more glycerol which lowers the freezing point of their blood; in short they produce their own anti-freeze. Even so, they still need to find somewhere sheltered from the coldest winter weather and this is the reason for us finding occasional butterflies in out-houses, and even spare bedrooms at this time of year.
We have at least four species of butterfly (including brimstone, small tortoiseshell, comma and peacock) which can over winter in their adult form in Britain. During winter they often wake, aroused by the warmth of the sun, or our central heating, and fly around for a few hours before settling down to sleep again. It is obviously better for them if they can remain in hibernation until such time as there are flowers from which to find food.
The ladybird is another insect which hibernates in Britain. They tend to tuck themselves away in amongst ivy, or maybe in cracks around our windowsills, but many find themselves in the bark of evergreen trees. As a result we might accidentally bring them into our houses on Christmas trees.
If you find one hibernating ladybird there is a good chance of there being more because when these delightful insects locate a suitable hibernating space they excrete a pheromone to attract others. Gardeners have good reason for trying to attract and look after their ladybirds. For one thing they eat aphids and greenflies; it is much better to have ladybirds on hand than to use chemicals to tackle this problem.
One of the most likely moth species to be found in the home over winter is the herald moth. This species has a flight season which begins in autumn and concludes in spring. Between the two periods it hibernates in cellars, caves, sheds and sometimes houses.
What to do when hibernating insects wake up
If you have insects which are trying to hibernate in your house but which keep waking when the central heating comes on the best thing to do is to catch them and move them to an environment with a more constant temperature, such as a shed or garage.
When you find hibernating ladybirds on your Christmas tree the ideal solution is to move the whole tree outside to a sheltered location.