Although insect larvae may seem harmless to humans, they can be extremely dangerous to the plant species that many of them feed on, and some of those plant species are important as agricultural crops. Although plants cannot simply flee from danger like animals typically would, many have nonetheless evolved ingenious strategies to defend themselves from herbivores. Herbivorous insect larvae will commonly use their mouths to smear various digestive proteins onto plants that they want to eat, and when plants detect chemicals commonly found in these oral secretions, they can respond to the injury by producing defensive molecules, including proteins and specialized metabolites of their own that inactivate the insect's digestive proteins and thus prevent the insect from obtaining nutrients from the plant.