The family Braconidae is one of the largest in the Hymenoptera, containing more than 15,000 valid species (87). Together with the Ichneumonidae, it forms a distinctive superfamily among the assemblage of hymenopterans known as the parasitic wasps (39). Adult braconids oviposit almost exclusively in, on, or near other insects, with the immature stages completing their development at the host's expense. The terms parasitoid and protelean parasite are frequently applied to the various wasps, flies, and beetles that develop in this fashion. Many parasitoids are closely attuned to their hosts and have thus been of primary importance in the biological control of insect pests. Braconids are among the foremost of these beneficial insects. In classical biological­ control programs, their success rate is exceeded only by that of aphelinids (43, 60). Braconids are also widely used as models for the study of host-parasitoid interactions, and in this regard, an impressive number of recent contributions have encompassed the broad disciplines of physiology, behavior, and evolutionary biology. Clausen's book (19) includes a detailed review of the older literature on braconid biology, and this classic text still serves as an excellent source for general information on parasitic Hymenoptera. More recent volumes (39, 45, 136) provide additional insights into braconid biology and illustrate the diversity of research now being conducted on parasitoids. Several works (9, 87, 121) summarize braconid host relationships by subfamily, and a handbook on braconid classification and biology is now available (94). The exhaustive treatment of braconid biology contained in this handbook is an excellent review of the subject and will undoubtedly become the standard introductory reference for this family. The term bionomics is ideally suited for this review, which focuses on the