202 



directly due to the attacks of blowflies cost Australia over five millions sterling 

 per annum. 



The time of the year when these flies are troublesome to sheep varies in the 

 dififerent parts of the Commonwealth and even in different years in the same 

 district. Cooper collected information regarding blowfly prevalence and tabu- 

 lated it in 1913. The worst periods were stated to be from March to May, and 

 September to October, with some infestation in certain localities during winter 

 (June to August), but probably none during summer (December to February). 

 The chief periods are during autumn and lambing time. In Queensland, flies 

 make their presence felt whenever there is a good fall of rain (1 or 2 inches), 

 regardless of the time of the year (R. S. C, 1922, p. 45), and sheep may be 

 badly attacked during the period February to October (R. S. C, in Knibbs, 

 1922). Froggatt (1913, p. 15) stated that warm showery winters are especially 

 favourable for infestation which may appear as early as March, or may be 

 delayed till several months later. Place mentioned in 1922 that infestation was 

 not especially noticed in South Australia until ten or twelve years previously, 

 and that it occurred particularly in March, April, or May (being worst in the last- 

 named month), and again in spring. These periods correspond approximately 

 with those in Tasmania, Victoria, and New South Wales. In New Zealand, 

 Miller (1921) reported that though infestation might occur in winter, it was 

 especially prevalent during lambing season in the spring, continuing to December, 

 and appearing again in the autumn. Gilruth called attention to its occurrence 

 in summer in North Otago, in the Dominion (1907). 



In the earliest accounts of Australian infestation, the culprits were reported 

 by Froggatt (1905, 1910) to be the two commonest native blowflies, Calliphora 

 oceaniae, and C. villosa, now known as Anastellorhina augur, Ydhr., and A. 

 stygia, Fabr., respectively (Johnston and Hardy, 1922), The latter occurs also 

 in New Zealand as a sheep maggot-fly (Miller, 1921). Woodburn (in Cooper, 

 1913) stated that the "hairy maggot" (i.e., the larva of Chrysomyia alhiceps) 

 was one of the worst offenders, while Froggatt later (1913) included it (as 

 Calliphora rufi fades) along with the two mentioned, but stated that it was of 

 minor importance. Several other flies were referred to by him, but it was stated 

 that they had not been bred from live wool, though they had been bred out from 

 carcases. They were C. varipes, Lucilia sericata, L. caesar, and Ophyra nigra. 

 Subsequently some of these were reported as blowing wool on sheep. In 1915 

 the same author stated that C. alhiceps was the chief blowfly of sheep, and gave 

 an account of the main flies and their larvae, adding species of SarcopJiaga 

 to the list (1914b, 1915). The species which have been reported by Froggatt 

 as breeding in wool in Australia are A. augur, A. stygia, C. alhiceps, C. varipes, 

 L. sericata, Sarcophaga sp., and Ophyra nigra. Taylor (Proc. Linn Soc. N.S. 

 Wales, May, 1920) stated that Lucilia fuscina, Wlk., was one of the sheep 

 maggot-flies in Queensland, where it had been confused with L. sericata. The 

 writer of this article has also pointed out that more than one species is included 

 under this latter term in Australia (Johnston, 1921, p. 245 ; 1922, p. 273 ; Johnston 

 and Tiegs, 1922, p. 79). 



It is not yet known whether one kind of blowfly leads the attack and sets 

 up conditions which attract others. The following facts are of interest: — (1) 

 Ihat the commonest blowflies, A. augur and A. stygia, not uncommonly blow 

 woollen materials (blankets, bales, etc.) ; (2) that they were the first reported by 

 Froggatt as infesting sheep; and (3) that one of them has been recorded by 

 Miller as causing trouble in New Zealand. They suggest that these flies may 

 be the primary cause. As species of Lucilia are known to be culprits in Great 

 Britain, South Africa, and New Zealand, it is not unlikely that they may act 

 similarly in the Commonwealth, where they are very common around carrion. 



