ABSTRACT
The pupal parasites were placed in the field inside mesh bags. The action of the natural enemies on the flies was evaluated on seven occasions, sampling different fly development media each time. The effect of the pupal parasites was evaluated by retrieving the pupae from soil near or beneath cattle dung, with a series of sieves. Parasitism in general fluctuated considerably between sampling sites and the years. A long drought period had occurred from November 1986 to mid February 1987. The feces originating from feeding on tender growth seemed to be very suitable for fly development. A maximum of forty adults per square meter of dung were recorded. The adults were also observed preying on the neonatal adult flies as they emerged. A biological control program of filth flies was initiated in Easter Island from 1982 onwards.
