“The Chewing bite of a caterpillar on a leaf of barrel clover will make the plant produce jasmonic acid, whereas the tiny piercing bite of a spider mite will cause the plant to make salicylic acid instead.”
Riskin, Dan. 2014. Mother Nature is Trying to Kill You.
Leitner et al. Direct and indirect defense induced by piercing-sucking and chewing herbivores in Medicago truncatula. New Phytologist Vol. 167. Issue 2. 2005