none BRACONIDAE-; HEMIPTERAN-HOSTS; Dysaphis plantaginea; Prevalence; ITALY-; Parasitism of hemipteran host, effect of Formicidae (Hymenoptera) FORMICIDAE-; ASSOCIATIONS-; Dysaphis plantaginea (Hemiptera); Effect on hymenopteran parasite prevalence, Italy Dysaphis plantaginea; ASSOCIATIONS-; Formicidae (Hymenoptera); Effect on hymenopteran parasite prevalence; HYMENOPTERAN-PARASITES; Braconidae; Prevalence, effect of Formicidae (Hymenoptera); ITALY-; Hymenopteran parasitism, effect of Formicidae In 1992 and 1993 a trial was carried out into the influence of ants on parasitoids of rosy apple aphid (Dysaphis plantaginea (Pass.)) On the half of trees the movement of ants was impeded by adhesive bands placed around the trunk and covered with a ring of glue. In both 1992 and 1993, on the trees protected from ants, a significantly higher percentage of parasitism was observed than on the trees where ants could move freely. There was, however, a low incidence of parasitism even in the trees that were protected from ants with glued bands. The activity of parasitic wasps, belonging to the species Ephedrus persicae Froggatt, was delayed in the time and probably limited by hyperparasites (Hymenoptera Megaspilidae and Pteromalidae).