Field assessments of the impact of night-flying dung beetles (Coleoptera: Scarabaeidae) on the bush fly, Musca vetustissima Walker (Diptera: Muscidae), in south-western Australia

The effect of excluding the night-flying dung fauna, which included one abundant species of dung beetle (Scarabaeidae) in each of two areas, on the numbers of Musca vetustissima Wlk. emerging from cattle dung pads was studied in south-western Australia. Fresh dung pads were exposed to natural, daytime oviposition by M. vetustissima and half were covered at night. A test at one site before dung beetles emerged showed no effect of other nocturnal fauna on fly survival. In three experiments where Onthophagus ferox Har. was excluded, the numbers of flies emerging increased from 679 to 1019 per dung pad. In five experiments where Onitis alexis Klug was excluded, the number of flies emerging increased from 14 to 33 per dung pad. The mortality contributed by Onthophagus ferox was estimated to be around 27% and that by Onitis alexis around 15%.