THE LIFE-HISTORY OF THE YELLOW DUNG-FLY. 629 



34. Tlie Life-History and Habits of the Yellow Dung-Fly 

 [Scatophaga slercoraria) ; a possible Blow-Fly ('heck. 

 By G. S. CoTTERELL. With a Preface by Prof. Max- 

 well Lefroy, F.Z.S.* 



(Text-figures 1-14.) 



[Received October 19, 1920 : Read October 19, 1920.] 



Preface. 



This paper is an account of work undertaken to complete an 

 inquiry into Blow-li}^ control, of whicli a partial account has 

 ah-eadj been pubUshed by Mr. A. M. Altson in the Proceedings of 

 the Zoological Society, 1920, p. 195. Of the three important 

 controls of Blow- fly in England, Mr. Altson has already dealt with 

 the two common parasites : the present paper deals with what we 

 believe to be the most important direct enemy of the adult fiy, 

 a check which appears to be very efi'ective in this country. The 

 Yellow Dung-fly first showed itself in our work at the Zoological 

 Society in 1915 in connection with methods of trapping flies: it 

 came in numbers, persistently eating the adult Blow-flies, and 

 seriously interfered with experiments out of dooi's. My observa- 

 tions since show that while the fly preys on a large variety of 

 Diptera, ifc specially attacks Callipliora and Masca. It is a 

 constant and general feeder on the common species of Blow-fly in 

 England throughout the season. 



The author of this paper undertook the investigation, and 

 submitted tliis j)a'Per as a thesis for the Diploma of the Impeiial 

 College : he also investigated the best means of transporting this 

 species to countries where Blow-fly is a serious pest to sheep, in 

 the hope that it might be possible to utilise it as a check on 

 Blow-fly. This has not been possible as yet, but the species 

 seems to have much value in this connection, and its habits as a 

 maggot and an adult are so harmless that it is to be hoped it 

 will eventually be made use of. — H. M. Lefroy. 



Introduction. 



The study of the life-history and habits of the Yellow Dung- 

 fly was first commenced in October 1919, at a time when the 

 Blow-fly problem was receiving a great deal of attention and 

 the discovery of an eflicient control was sought for. 



In conjunction with other methods of control then under 

 investigation, that of the Yellow Dung-fly, as a predator on the 

 Blow-fly, was also studied. 



The adult fly was identified for me by Mr. Edwards, of the 

 Natural History Museum, South Kensington, as Scatophaga 



* Communicated bj- Prof. Maxwell Leeeot, F.Z S. 



