The host foraging behavior of the larval parasitoid Diachasma alloeum (Muesebeck) (Hymenoptera: Braconidae) from natural populations was directly observed in a highbush blueberry, Vaccinium corymbosum L., plantation. More D. alloeum were observed alighting on blueberry fruit clusters infested with Rhagoletis mendax Curran larvae than were observed alighting on uninfested blueberry fruit clusters 80 cm away. Approximately equal numbers of D. alloeum alighted on uninfested blueberries that were mechanically damaged versus undamaged. The majority of D. alloeum females were attracted to host-infested blueberries 15 to 21 days after R. mendax females had oviposited into fruit. Female D. alloeum spent more time alighting on R. mendax-infested blueberry fruit clusters than on uninfested blueberry clusters 80 cm away. There was no difference in the duration of time spent by D. alloeum on mechanically damaged versus undamaged uninfested blueberries. The data herein are an initial step toward elucidating the cues mediating microhabitat selection by D. alloeum in blueberries. Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Land zones; Nearctic region; USA; North America Rhagoletis mendax (Tephritidae); Hymenopteran parasites; Diachasma alloeum; Parasite attraction to host on fruit; Plant hosts; Vaccinium corymbosum; Michigan; Fenneville; Hymenopteran parasite attraction to host on fruit Diachasma alloeum (Braconidae); Dipteran hosts; Rhagoletis mendax; Parasite attraction to host on fruit; Michigan; Fenneville; Attraction to dipteran host on fruit none