Common Drone Fly

Eristalis tenax is a hover fly, that mimic bees.

"The common drone fly belongs to the migratory insects and performs directed seasonal migrations. In autumn, these lead from Central Europe south and south-west to the Mediterranean region. The dung bee crosses the passes of the low mountain ranges, the Pyrenees and the Alps. In the spring, migration is in the opposite direction. The dung bee moves using favorable winds and avoiding unfavourable ones. It exhibits behaviour similar to that of migratory butterflies and birds." (*Wikipedia)

"In ancient times there was a superstition that bees (because of the honey) could be raised by letting an ox rot in the field (spontaneous generation) - the masses of fly maggots like e.g. T. have really produced dung bees, but this hardly led to more honey." (*Wikipedia; the German name is dung bee)