A plague gnat was a small green gnat that infested swampy terrain. Their bite could cause plague gnat boils, a disease that caused large red sores that themselves could contain plague gnats, which, if left untreated, burst into a cloud around the victim.[1]


  1. Jason Bulmahn (September 2005). “Swamp Dangers”. Dungeon #126 (Paizo Publishing, LLC), p. 93.