PHENOLOGY AND ECOLOGY OF HOVERFLIES (DIPTERA, SYRPHIDAE) IN NEW-ZEALAND

Hoverflies are potentially important in many agricultural and horticul tural crops as biological control agents. The two most abundant specie s of hoverflies present in the New Zealand agricultural landscape are Melanostoma fasciatum (Macquart) and Melangyna nouaezelandiae (Macquar t), both of which are aphidophagous and also prey on young lepidoptera n larvae. Information regarding the phenology and ecology of these spe cies is quite limited but is needed if the contribution of these preda tors to biocontrol is to be enhanced. The main work reported here conc erns the trapping of large numbers of hoverflies to investigate their phenology; these flies were subsequently assessed for the pollen type taken and for wing wear. Foraging behavior, optimal trap color and ide al trap-emptying rate were also studied. There was good evidence of a second generation of hoverflies occurring in late summer and pollen pr eferences for both species of hoverfly ere exhibited. The foraging beh avior of the two number of flights made and the overall distance trave led over fixed time intervals. Yellow was the most efficient color for trapping M. novaezelandiae but for M. fasciatum yellow, white, and bl ue did not differ and green was poor. The value of the work in providi ng background ecological information for possible enhancement programs for hoverfly populations on farmland is discussed.