One of the fundamental questions in evolutionary ecology seeks to understand how new biodiversity is created and structured into communities. The apple maggot, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), a model for rapid ecological speciation via host plant shifting for phytophagous insects, and its parasitoid community can offer insight into answering this and other related questions. Speciation of Rhagoletis also seems to be driving sequential speciation in a host specific parasitoid wasp Diachasma alloeum (Muesebeck) (Hymenoptera: Braconidae). However, biological and geographic information regarding D. alloeum and other parasitoids attacking flies in the genus Rhagoletis is sorely lacking, a problem that complicates the study of their evolution. Here, we present a synthesis of the geographic ranges and extended host associations of Rhagoletis-attacking parasitoids and test whether parasitoids can overlap in host use. In particular, we ask whether 1) wasps that co-occur in sympatry attack different life stages of the fly, 2) locally co-occurring wasps share some fly species in common but not others, 3) wasps differ in local abundance on those fly hosts they share in common, and 4) wasps vary on a regional scale in their geographic distributions. We use both collections and published records to answer the above-mentioned questions. A strong understanding of the Rhagoletis-attacking parasitoid distributions will facilitate future study of sequential radiation in this system.