Oogpister beetles are able to shoot formic acid into the eyes and mouth of would-be predators. In this BBC video you can see an oogpister teach a mongoose a painful lesson.
We also meet a defenseless lizard that has developed the same marking pattern on the oogpister beetle’s shell in order to trick predators into thinking that it, too, can shoot acid from its rear end. So fearsome is the oogpister’s reputation, that the lizard even imitates the way the oogpister runs.
The video also features a stick insect that “fires bitter tasting oils,” and ants that “fire the sort of acid that gives nettles their sting.”
It concludes with the biggest badass chemical weapon bug of them all: the fearsome bombardier beetle. “It can create a chemical reaction within its body so violent that boiling caustic liquid explodes out of its abdomen.” It pulses the jet of acid 500 times a second to keep “its rear end just cool enough to prevent it from being cooked.”