Herbivory is one of the major ecosystem processes, as are pollination and seed dispersal, which drives ecological changes in both the phytophagous fauna and their host plant assemblages. The amount of herbivory damage on a host species represents not only the amount of herbivory pressure due to phytophagous insects but also the predatory pressure due to predators at higher trophic levels. Furthermore, additional interactions of climate and environmental factors determine the conditions of the host species and subsequently the assemblage of herbivorous insects that colonize them. All these direct and indirect, positive and negative influence of climate and environmental factors combined with the requirement to propagate themselves cascades to through the higher trophic levels down to assemblage of herbivorous insects and their host species at the lower trophic levels. This study considered the host specificity of caterpillars, herbivory pressure and herbivory damage on trees and shrubs along an altitudinal gradient within subtropical and temperate rainforest. The work has attempted to show how a selected ecological process (herbivory) is being influenced by various factors including altitude, ant predation pressure and host plant species, canopy strata and physical properties of leaves.