Synopsis In this book due emphasis has been laid on the characteristics of disease-carrying insects to render their identification with certainty. Their life history and bionomics have also been adequately dealt with on which the control measures are based. Its scope has, however, been widened by including the behaviour of the parasite during the "insect phase" in its life cycle. The Medical Entomologist, a biologist and a parasitologist at the same time. The book has, therefore, been written to satisfy the needs of the entomologist in order that he may fulfil these difficult functions without any undue strain on him. Though this book has been written with the primary object of giving an account of insect life and the behaviour of such insects towards the spread of disease organisms in this country, information on similar lines in respect of other countries has also been incorporated though in a comparatively brief manner. A book giving a total picture of insects of the entire world and their parasitological relationships is a necessity for every entomologists and parasitologist.