Herbivory is a paradoxical interspecific interaction. On the one hand, upward of a quarter of all species are herbivorous insects (Strong et al., 1984) and some additional fraction of the noninsect species is also herbivorous, so plant-herbivore interactions are common. On the other hand, the simple observation is that, to a first approximation, the earth is green (Hairston et al., 1960), despite the combined effect of those herbivores.
Source: wiktionary