pdf none Larvae of a ranunculus leaf-mining fly, Phytomyza ranunculi Schrank, mainly feed on the palisade parenchyma of the leaflet of the host plant, and produce a serpentine mine. These larvae are attacked by many species of parasitic wasps in the field. These parasitoids appear to employ the mine as an important cue not only to the host-patch location but also to the host location on the leaflet. The authors conducted experiments to establish what properties of the host mine these parasitoids respond to when searching on leaflets.