The effectiveness of three species of scarabaeids in reducing the survival of Musca vetustissima Wlk. in cattle dung was compared in laboratory experiments in Australia at 27°C in which the arthropod fauna collected in dung-baited traps in different localities at different times of year was added to one-litre dung pads containing known numbers of M. vetustissima eggs. The dung was collected from each site at the time of the experiment. Onitis alexis Klug collected in October and December at Geraldton, and Onthophagus binodis (Thnb.) collected in January at Bunbury, shredded most of the dung, reducing fly survival to 4% of that in control pads. O. binodis collected in March and October at Bunbury, and O. ferox Har. collected in May and December at Busselton, mostly buried dung, reducing fly survival to 32% of that in controls. Factors other than the numbers of beetles were also important in determining the degree of suppression of the fly.