This year saw a mass of Painted Lady Butterflies arrive in Britain and they are still around. Butterflies go to sleep in the Winter and like to find warm dark places that they can drowse in. They don't actually hibernate so they are using energy even though they are not very active.
To tell you about our experience this year may sound quite familiar, so we hope it might help.
back in November we noticed three or four Painted Lady Butterflies on the window sills around the house, thought nothing about it other than we were blessed to have so many, but as Winter draws on, we notice they move around from time to time, sometimes they are not so smart, and chose to fly down from the window sill to the carpet and it is only by luck that we saw them and did not tread on them.
We tired a few times to move them from the window sill or carpet onto another sill, but they always returned to their favorite spot. Unfortunately one of them died on the window sill, so we were concerned about that. What we decided to do was to put some sugared water on a clean cloth and put it in front of the two remaining Butterflies - they moved towards it and drank their fill! we were so pleased. It appears they are not fully equipped to survive the Winter and so if you feed them then they really do appreciate it.
We do sell Butterfly houses and food, but sugared water is good to get them through - give it a try!