Treats all aspects of black flies in a worldwide perspective, including natural history and ecology, cytology and morphology, phylogeny and classification, economic impact, pest management, natural enemies, history of research, study methods and identification. Each of the 254 species known from the continent north of Mexico, including 43 new species, is treated in detail. Each species account summarizes all pertinent information on taxonomy, morphology, cytology, physiology, molecular systematics, and bionomics.