The Plague of Frogs
jpbostic writes "According to this article on MSNBC, ag folks in Hawaii were considering using powdered caffeine to help rid themselves of an infestation of frogs from Puerto Rico. The EPA's application regulations apparently proved too burdensome and the stuff sits in a warehouse. If the EPA is really concerned with the danger, they should investigate the coffee in some restaurants *quoth the caffeine addict*. :-)"
... Or the episode where Springfield is overrun with lizards, and Principal Skinner suggests they unleash wave after wave of creatures to prey on the previous waves...