Lesley's Nature Watch - Where do Butterflies go in Winter?

There is no single answer to this question as different species do different things. Some species such as the smaller Skipper butterflies, overwinter in their egg form. Many others hibernate as catterpillars,e.g. Large Skipper, Meadow & Heath Browns.
Orange Tips & many others overwinter in pupa form while Peacocks, & Speckled Wood are amongst those who spend the winter in hibernation as adult butterflies, often in our sheds, attics & outbuildings. This why, on the first warm days of the year, we can see some very tatty individuals of these species sunning themselves. Conversely, those who passed the winter as chrysalis will now come out as butterflies & look immaculate! The Painted Lady Migrates south for winter which was so wonderfuly witnessed when huge numbers returned on mass in the spring of 2009. Whatever happened to them all remains a mystery.
The Swallowtail (pictured) has an interesting survival tactic. The female lays several individual eggs. Some of those will complete their life cycle in the same year, while others will remain in their pupa form until the following spring.