Crabgrass, the killer weed, inflicts chemical warfare on lawns and farms.
Learn how the rabbit population in Australia rose to six-hundred-million over the course of 100 years. "Rabbits Down Under" on this Moment of Science.
There is a war going on between a certain tropical butterfly, Heliconius sara, and its only food source, the passion vine. This war involves chemical warfare. More precisely, the plant arms itself with cyanide bombs that are rather useful in getting rid of most insect pests.