When ants attack. #47
Caterpillar being attacked by an ant, spat some green fluid at it.
When annoyed by a predator (or other critter like a nosy human) some species of caterpillars 'spit'. Quoting a well-known local Lepidopterist, "this green regurgitated fluid is from the gut and is supposed to be purely a defensive action (startling a predator)".