THE PHENOLOGY OF THE NATIVE DUNG BEETLE ONTHOPHAGUS-AUSTRALIS (GUERIN) (COLEOPTERA, SCARABAEINAE) IN SOUTH-EASTERN AUSTRALIA

Onthophagus australis (Guerin) is predominantly univoltine at two sites in south-eastern Australia, with Peaks Of activity in spring when most oviposition takes place, and in autumn when the new generation emerges. It overwinters mainly in the adult stage, and populations decline during summer droughts. The optimum temperature for oviposition is between 20 and 25-degrees-C, and the beetle produces food balls intermittently throughout life. The threshold temperature for development was estimated to be 5.2-degrees-C, and 1612 day-degrees (degrees-C) are required for development from egg to adult. In the laboratory, 100 beetles in a 1-L dung pad are able to reduce bush fly survival by 74%, and reduce the size of the fly puparia by 18%. In spring, when bush flies first build up their populations in the field, numbers of 0. australis did not often reach 100 per pad, thus limiting their usefulness for the biological control of the bush fly.