This book attempts to summarize what we know about inseet-plant
relationships without beeoming too involved with untestable hypo-
theses. It is not intended to be eomprehensive and we have deliberately
excluded diseussion of aquatie organisms and fungi. Our definition of
inseet herbivores is intentionally broad. It includes all inseets whieh
feed on plants, although we have emphasized those whieh feed primarily
on the photosynthetie tissues. Some referenee is made to seed predation
but pollination eeology is excluded. We thank Ors P.H. Smith and M.
Luxton for their helpful eommenb on the manuseript but we accept full
responsibility for any mistakes whieh may remain. Finally, we thank the
various publishers and a uthor who gave us permission to use copyright
material. 7 I Introduction The net primary produetion of the 300000
speeies of vaseular plant whieh inhabit the dry land surfaee of the
earth has been estimated at 9 about 115 x 10 t per annum. This
represents a massive resouree potentially available for exploitation by
the herbivorous inseets, which themselves probably number in exeess of
500000 species.