The perennial monocarpic endemic species Heracleum platytaenium Boiss. [Apiaceae (=Umbelliferae)] was collected with associated insects in Kizilcahamam (Ankara) between June and August in 2006-2007. Nine insects, namely Hemipterous Graphosoma lineatum (L.), G. semipunctatum (Fabricius) and Anoraphis subterranea (Walker), Coleopterous Lixus nordmanni Hochhuht. Lepidopterous Aethes kasyi Razowski. Epinotia thapsiana (Zeller) and Epermenia chaerophyllella (Goeze), Dipterous Melanagromyza heracleana Zlobin, and Lasiambia albidipennis (Strobl.) (Diptera) were determined on H. platytaenium. Among them, M. heracleana (Agromyzidae) is recorded from Turkey for the first time, and Lasiambia albidipennis (Chloropidae) is new as genus and species for the Turkish fauna. Additionally. H. platytaenium is recognized as new host for 5 species: A. subterranea, A. kasyi, E. thapsiana, E. chaerophyllella, and M. heracleana.