One of the few whole-tree herbivory estimates was conducted in Walcha, New South Wales, Australia with Earthwatch volunteers in 1985. Over 100,000 leaves were measured for length, width, leaf area, and insect damage. Over 20 Earthwatch volunteers gave their time and energy to this survey, which was critical in solving the eucaylpt dieback syndrome that devastated Australia in the mid-eighties (of note: now we recognize those drought and weather-related insect outbreaks as part of a climate change syndrome). This powerpoint, created by New College student Erik Walimaa, summarizes some of this data on whole tree herbivory.
