Plants are subjected to a multitude of stimuli during insect herbivory, resulting in a complex and cumulative defence response. Breaking down the components of herbivory into specific stimuli and identifying the mechanisms of defence associated with them has thus far been challenging. Advances in our understanding of responses to inconspicuous stimuli, such as those induced by microbial symbionts in herbivore secretions and mechanical stimulation caused by insects, have illuminated the intricacies of herbivory. Here, we provide a synthesis of the interacting impacts of herbivory on plants and the consequential complexities associated with uncoupling defence responses. We propose that simulated herbivory should be used to complement true herbivory to decipher the mechanisms of insect herbivore-induced plant defence responses. Ground-breaking research into the chemical and biochemical signals of plant defences has dramatically increased our capacity to understand many of the details that underpin plant–herbivore ecology. Herbivore-associated microbes, chemical elicitation, and mechanical stimulation are all known to activate diverse signalling pathways. True herbivory can be useful to obtain information on the collective plant response, but it cannot disassociate mechanistic responses of specific defence pathways triggered by the different stimuli associated with herbivore feeding. Simulating the chemical and physical factors associated with herbivory in isolation will allow us to disassemble plant defence responses and understand which stimuli are associated with a given defence response.