Nature: Butterflies fly in on wings of a storm

Hundreds of thousands of small tortoiseshell butterflies (above) have flown into Britain from Europe over the past two weeks after being caught up in storms off the French and Spanish coasts.

The insects, whose caterpillars feed on nettles, have been arriving in huge numbers across England's eastern coastline to boost the resident population of small tortoiseshells. On one kilometre-long stretch of coastline observers estimated that 40 were flying in every minute. It is thought that the mass movement began when storms in the Bay of Biscay, hundreds of miles to the south, at the end of August, blasted the butterflies north. Another common species, the small white, has also been seen in larger numbers. The small tortoiseshell, often seen in gardens, will soon go into hibernation. If you find one in your home, putting it in a cool, sheltered place like a garage gives it the best chance of surviving the winter.