Selected citrus peel oils and oil constituents were tested for toxicity to eggs and larvae of laboratory-reared and wild Caribbean fruit flies,Anastrepha suspensa(Loew). In general, the responses of both laboratory-reared and wild fly eggs to these agents were quite similar. In contrast, laboratory-reared larvae were more susceptible than wild larvae to all test agents. Possible explanations for the observed difference in larval susceptibility are presented.