If you’re playing the experimental, you may notice little dots flitting around at times, these are new “vermin” that were recently added. They’re mostly harmless, though in the future some of them might get nasty stings or some such (think actual bees, wasps, spiders). There’s a bug in the overkill code right now that causes killing some of them to create a 6x6 area covered in blood.
Jus reporting so people know it’s a known issue… and because it’s funny.