Arriving in Italy we found our apartment had been squatted in by a swarm of hornets, probably through the chimney. It appeared they’d recently had a massive party and most, but not all had died.
We started a fire to clear the chimney and dispose of the corpses, which given how gigantic they were, was a lot of burning. By a lot, I mean dustpans full of hornets, some still crawling, at a time.
They could have been European Hornets, but the largest were closer to 5cm or so, fairly large even for European Hornets.