This is the most current key to the 40 species of Cuterebra bot flies in North America. The key is meant for having the specimen in hand, and not all species are pictured, so takes some effort to use the key. But nice range maps and packed with information about each species of bot. Excellent bibliography for more detailed information, if desired. This is the best book on bots out there, but those not familar with terminology may struggle with it.