Small Tortoiseshell Butterfly. (Aglais urticae)

Today I was having a bit of a sort out and moved some books on shelf.  They hadn't been moved for along while.  Behind them I found this sad little body.

I assume it either came into the house to hibernate and failed to make it through a winter.   The alternative is it survived over a winter but died because it couldn't get out of the house.  In view of its position I would suggest the former cause of death most likely.

While on the subject of Butterflies hibernating, if you find one fluttering against the window during winter don't let it out.  It has been inside hibernating and the warmth of the house has wakened it.  Instead of letting it out pop it in a small box or container and put it in the fridge.   Then it will go back to sleep.  Once it is asleep you can find a dry protected crevice outdoors and carefully slip it in.   Then when the time comes for it to wake up it will be able to continue its life safely.