Principles of Insect Pathology, a text written from a pathological viewpoint, is intended for graduate-level students and researchers with a limited background in microbiology and in insect diseases. The book explains the importance of insect diseases and illuminates the complexity and diversity of insect-microbe relationships. Separate sections are devoted to the major insect pathogens, their characteristics, and their life cycles the homology that exists among invertebrate, vertebrate, and plant pathogens the humoral and cellular defense systems of the host insect as well as the evasive and suppressive activities of insect disease agents the structure and function of passive barriers the heterogeneity in host susceptibility to insect diseases and associated toxins the mechanisms regulating the spread and persistence of diseases in insects. Principles of Insect Pathology combines the disciplines of microbiology (virology, bacteriology, mycology, protozoology), pathology, and immunology within the context of the insect host, providing a format which is understandable to entomologists, microbiologists, and comparative pathologists.