First published in 1914, this volume was written in response to rising concerns regarding the role of the house-fly in the dissemination of infectious diseases, and its relationship to unhygienic conditions. Given the role played by the house-fly in these circumstances, it was decided that a thorough study of its entomological and medical significance was required. The volume was not intended as a popular treatise on the subject, this role had already been fulfilled by the author's House-flies and How they Spread Disease. Instead, it was designed for professionals in entomology and public health, together with students developing a specific interest in these areas. Numerous detailed illustrations of house-fly anatomy are included. This book will be of value to anyone with an interest in entomological studies and the history of public health.