Entomology is the branch of zoology, which deals with the scientific study of insects. It focuses on how insects interact with the environment and other species. It plays a crucial role in the assessment of environmental quality and study of biodiversity. There are many sub-specialties of entomology such as coleopterology, dipterology, melittology, myrmecology, lepidopterology, odonatology, etc. Medical entomology is concerned with the medical research of insects and their impact on public health. It also studies plant damage and diseases that are caused by insects, along with effectiveness and development of pesticides. Economic entomology is associated with the study of harmful and beneficial impact of insects on humans, animals and crops. This book aims to shed light on some of the unexplored aspects of entomology. It is a valuable compilation of topics, ranging from the basic to the most complex theories and principles in this field. This textbook will provide comprehensive knowledge to the readers.