The Peacock Butterfly is one of the few British species that overwinter as mature adults. They will frequently find a hole in a tree, an outbuilding or other sheltered space in which to spend the colder months. Often these places are regularly frequented by several insects and are used year after year.
Last week I was told of a roosting site and upon inspection there were around thirty insects present. Camouflaged by their drab under wing just occasionally one would flash its coloured upper wing in an attempt to scare away intruders, perhaps detecting our presence. Thirty Butterflies are not something you would expect to see on a very cold February day.