168 The Effect of Various Chemicals on Blow -Fiji 



though a very important question, is outside of the province of this 

 paper. 



The Maggot-fly species, chiefly responsible for the damage to sheep 

 in Australia, are Calliphora oceaniae, C. villosa, C. rufifacies, and Lucilia 

 caesar. It is impracticable to employ any of these species for experi- 

 mental work in this country, and, as the exact species is of little import- 

 ance in preliminary work, for reasons specified above, the larva of the 

 common "blue-bottle" (Calliphora vomitoria) was used. 



At first, the larvae were all bred from flies captured locally. Large 

 pieces of horse-flesh were exposed in a room, suitable precautions having 

 been taken to prevent the escape of the flies, and a moderate supply of 

 larvae was readily obtained. Owing, however, to the large number of 

 chemicals for trial, this supply of maggots was inadequate, and larger 

 supplies had to be obtained from a dealer in angling requisites. Buckets 

 of cow manure had been placed in the breeding room, as it was thought 

 that this might hasten the development of the flies, and, as prior to the 

 introduction of purchased maggots and the cow manure, healthy larvae 

 were always obtained, we suspect one or other of these as the source 

 of the chalcid infection which upset our experiments. The mortality 

 in our controls so long as we were using home-reared larvae was usually 

 very low, and rarely exceeded 10 % . In the later experiments, how- 

 ever, the mortality in the controls increased to an excessive degree, 

 and in not a few cases exceeded that of the chemically treated larvae ! 

 The chalcid infestation increased to such a degree, that very few of the 

 pupae developed, and the investigation had to be abandoned 1 . 



A. Experiments with Compounds presumably deterrent to the Adult. 



For this purpose, slabs of horse-flesh, of about 1 lb. in weight, were 

 placed in shallow cardboard boxes, and the exposed surface dusted over 

 with the reagent, suitably diluted with precipitated chalk. The boxes 

 were then exposed to the flies. They were examined daily, and careful 

 note taken of any "blowing." Controls, of untreated meat, were 

 similarly exposed. 



1 The species of Chalcid fly which caused the trouble is unknown. Specimens were 

 sent to the British Museum for the purpose of determination, bul were reported as unknown. 



The astounding mortality caused by this infection suggests a means of controlling (lie 

 Blow-fly pest iii pastoral countries, and we have since heard that Mr Froggatt, Chief 

 Entomelogisl to the New South Wales Government, is carrying out experiments with 

 this end in view. 



