Notes on the ecology of the bushfly, Musca vetustissima Walk. (Diptera : Muscidae), in the Canberra district

Abstract

In the Canberra area Musca vetustissima has been bred from faeces of man, cattle, sheep, and dog. Other Australian records include dung of the horse and pig, and the paunch contents of dead ruminants. Bushflies first appear in Canberra in October. Maximum abundance is attained in December-January. No flies are present from late May to late October. The species may overwinter in the pupal stage. In December experiments marked flies were recovered up to 3.5 miles from the liberation point within 48 hr of release. Calculations suggested a population density of about 9000 bushflies per acre at this time. Catches of M. vetustissima in liver-baited blowfly traps differed from those of blowflies in not being markedly lower in treeless areas than in areas with trees and shrubs. The daily M. vetustissima flight activity pattern, as judged by trapping, was usually unimodal but there was some evidence of reduced activity in the early afternoon in hot weather. Air temperatures afforded a poor guide to the daily flight activity patterns of M. vetustissima, and the temperatures at which the first flies entered the traps in the morning were generally lower than those at which the last ones entered in the evening on the same day. The male to female ratio in trapped M. vetustissima was significantly higher than in any blowfly species, and the correlation between male to female ratio and total trap catch was lower than in blowfly species. The male to female ratio of M. vetustissima showed a distinct pattern of correlation with the male to female ratio of blowfly species.