Dispersal and effects of barriers on the movement of the New Zealand hover fly Melanostoma fasciatum (Dipt., Syrphidae) on cultivated land

Dispersal within agricultural fields and the effects of different barriers on between‐field movement of the New Zealand hover fly Melanostoma fasciatum were studied using ingested pollen as markers. Hover flies did not generally disperse more than 20 m from the pollen source. Gravid females had no significant wind‐directed movement pattern whereas males significantly flew downwind. Flies tended to avoid flying over barren land: a dirt track, an asphalt road or a ploughed field all seemed to hamper hover fly dispersal equally. The implications for spatial arrangement of the flowering strips to enhance the biocontrol potential of hover flies are discussed.