Abstract Increasing evidence suggests that, depending on the structural complexity of a plantation, it can act as complementary habitat for insectivore birds and mammals. The magnitude of interactions such as insectivory, in turn, have been determined by species’ richness and abundance in an ecosystem. Therefore, insectivory can vary in function of the plantation’s complexity, and thereby, decrease chance of plantations damage due to herbivorous insects. Through an experimental procedure, the insect larvae mortality risk in pine plantations with different degree of structural complexity was measured, together with the herbivory levels on Aristotelia chilensis related to each plantation type. Attacks to artificial caterpillars were significantly greater and herbivory significantly less in structurally complex plantations, where we found higher woody species richness and abundance and a greater understory development, compared to simple plantations. These results suggest that insectivory does vary in function of the structural complexity within forestry plantations, and it is greater in those with higher species diversity, mediating a trophic cascade effect over vegetation, significantly diminishing herbivory. Therefore, forestry plantations should be managed into more structurally complex ones in order to allow a win–win scenario, where maintaining a greater biodiversity increases the provision of useful ecosystem services for these plantations.