Marmelade Fly Episyrphus balteatus
The Marmelade Hoverfly (also known as Twin-barred Hoverfly) is not difficult to identify. Mind you, this is a rather small species. It is a remarkable species though, for adult females often overwinter. In most hoverflies it is the egg, larva or pupa overwintering. This species seems to be migrating: lots of adults travel to Southern Europe in autumn, even crossing the Alps. In the bottom picture the slightly weird looking larva of the Marmelade Fly. You should be happy to have it in your garden, though. It feeds on aphids exclusively.
