For more than 20 years insect/plant relations have been a focus for studies in ecology and evolution. The importance of insects as crop pests, and the great potential of insects for the biological control of weeds, have provided further impetus for work in this area. All this attention has resulted in books on various aspects of the topic, and reviews and research papers are abundant. So why write another book? It seems to us that, in the midst of all this activity, behavior has been neglected. We do not mean to suggest that there have not been admirable papers on behavior. The fact that we can write this book attests to that. But we feel that, too often, behavior is relegated to a back seat. In comparison to the major ecological and evolutionary questions, it may seem trivial. Yet the whole process of host-plant selection and host-plant specificity amongst insects depends on behavior, and selection for behavioral differences must be a prime factor in the evolution of host-plant specificity. In writing this book, we hope to draw attention to this central role of behavior and, hopefully, encourage a few students to attack some of the very difficult questions that remain unanswered.
