I just stepped out the door to take the flask of water to the tree, and at the crossroads I walked into a swarm of at least 32 hive drones.

I know there were at least that many because I used mass boil, and the message window only displayed results for 32 attacks.
Thanks goodness it was at night, and I was hidden in shadows, but because I was walking through the woods in the dark with no lights or magic, the result when I heard the buzzing noise and hit Tab was I almost fell out of my chair.
(Edit: waited for dawn to get this image. Here you go, JL. Some of them wandered away, and a couple more are hidden by the trees.)

Sheesh, I'm glad that didn't happen at a low level...
Third run through the game, and I've never seen anything like that.
Edit: And it repeats! Something be broken, I'm thinking, so never mind.