In the autumn of 1917 the writer received several letters from Mr L. C. Peters describing his experiences with flies hibernating in a large and very old house, situated in a large park at Frampton, near Kirton, Boston, Lincolnshire. Mr Peters' attention was directed first to the matter towards the end of October. On removing the window sashes the frames were found “black with flies.” After fumigation a bucketful of dead flies was removed from a single window frame, and about six bucketfuls from other infested windows. Only one side of the house was affected, but on that side the flies were found in the window frames on all three stories. “Ladybirds” were also present in large numbers.