Gillott’s thorough yet clear writing style continues to keep Entomology near the top of the class as a text for senior undergraduates, and for graduate students and professionals seeking an introduction to specific entomological topics. The author’s long-held belief that an introductory entomology course should present a balanced treatment of the subject is reflected in the continued arrangement of the book in four sections: Evolution and Diversity, Anatomy and Physiology, Reproduction and Development, and Ecology. For the third edition, all chapters have been updated. This includes not only the addition of new information and concepts but also the reduction or exclusion of material no longer considered "mainstream", so as to keep the book at a reasonable size.

Based on exciting discoveries made during the previous decade, the topics of insect evolutionary relationships, semiochemicals, gas exchange, immune responses (including those of parasites and parasitoids), flight, and the management of pests have received particular attention in the preparation of the third edition. Overall, more than 30 new or significantly revised figures have been incorporated.