none Five species of larval parasitoids were reared from Rhagoletis pomonella (Walsh) infested fruit of hawthorn, Crataegus, collected from several locations in southwest Washington over a four year period. A braconid, Biosteres melleus (Gahan), parasitized larvae infesting fruits of a native hawthorn species, Crataegus douglasii Lindl. Another braconid, Opius downesi Gahan, emerged exclusively from R. pomonella pupae reared from fruits of an introduced species of hawthorn, Crataegus monogyna Jacq. A pteromalid, Pteromalus sp., and two eulophids, Tetrastichus spp., attacked R. pomonella larvae infesting fruits of both hawthorn species. No parasitoids emerged from a total of 4385 pupae reared from apple. Percent parasitism of R. pomonella was higher in C. monogyna compared to C. douglasii fruits. The highest average levels of parasitism of R. pomonella in C. monogyna and C. douglasii fruits were 90% and 23% respectively. The kinds of parasitoids, their relative abundances and timing of parasitization on the two hawthorns was related to differences in fruit ripening patterns and its effect on the development of R. pomonella on these two hosts. Parasitization of R. pomonella by Tetrastichus spp. is a new host record. The detection of these species and Pteromalus sp. in southwest Washington are the first records of ectoparasitoids attacking this tephritid.