In the last two months our bathroom has been invaded by these beetles. They are about 2-3 mm long, dark brown, and move very slowly. They are on the walls and ceiling, and seem to be concentrated around the windowsill. They are getting to be a nuisance as every time we have a bath we have to clear out 8-10 of them before using it! Can you help please with identifying them and suggesting how to get rid of them?