Current information on energy intake and on respiratory metabolism in adult Anisoptera is reviewed. Daily food consumption has been found to be about 10-15% of body mass in several species. Pachydiplax longipennis requires at least 7.3 h of feeding time and 38 J of energy to acquire this food. Metabolic rate during rest and endothermic warm-up have been reported previously, but accurate data on flight metabolism are lacking. A method of calculating the latter is tentatively proposed. Results using this method show that flight metabolism may be extremely high in some species but may vary markedly with flight behavior. Such data could eventually permit construction of accurate energy budgets for Anisoptera. I suggest that energy requirements may place important constraints on reproductive behavior of these insects, and I present a series of testable hypotheses, some supported by preliminary data, about the nature of adaptations of mating behavior to energy requirements. Further studies of both male and female energetics may prove fruitful in efforts to gain a general understanding of reproductive behavior.