A few levels back I was killing the swamp hatchlings for the exterminator (the hatchlings, btw, didn't drop anything, darnit) and one of these things swooped in and started stinging me. Me being the little chicken froggy that I am immediately ran for the zone because at the time the buzzers were red to me.
Not sure about the level, though. They con yellow to a 13 shaman, so 20 seems a bit high.