Little bunnies in the shape of dust that hop around. They disappear after a short time, so you have to catch them quick. Can only be cleaned up by the player, not AVAs.
Catch enough of them to fill some kind of bunny meter. Once full, dozens of dust lumps from that location explode onto the scene.
Once my AVAs are fully upgraded and I got enough to cover the map, I start to focus a little less on vacuuming. My thinking is that it would make the day-to-day vacuum a little more engaging and rewarding at that point.