THE BLOW-FLY PEST. 
the Executive Committee, after consultation with the Queensland Spe- 
cial Committee, a plan for the modification and enlargement of the 
scope of work in connexion with the biological side of blow-fly investi- 
gation. His recommendations have been adopted. 
The scheme may be subdivided under four distinct headings, 7.¢.:— 
(1) The formulation of measures against the adult fly ; 
(2) Those which aim at controlling the larval or pupal fly; 
(3) Measures designed to prevent sheep from becoming 
attacked; and 
(4) Those designed to destroy maggots already present, and to 
minimize the effects, as far as the affected sheep are con- 
cerned—e.g., by means of appropriate dressings. 
First of all, under this classification comes the study of the adult 
fly. A considerable amount of work yet remains to be done to deter- 
mine the various species of flies which frequent sheep, especially those 
which breed in wool, &., on sheep. The question then- presents itself 
whether one or more particular species initiate the conditions, and 
become the means whereby others are induced to attack the infested 
sheep and aggravate the condition. The determination, if possible, of 
predisposing factors, and information regarding the seasonal preva- 
lence of the various flies are important factors. Another very 
important part of the work, in the opinion of Professor Harvey John- 
ston, and one which may indicate where sheep are more likely fo 
undergo infestation, is to ascertain the “locality prevalence” of the 
various flies. This could be attempted by a systematic distribution 
of various kinds of country during the different months—an area of 
from one to four square miles to be taken, including, if possible, forest 
land, open forest, downs, plains, sheep camps, and land in the vicinity 
of creeks and dams. Associated with this work is the systematic use 
5f traps of various kinds, to test which is the most effective for all 
species or for any particular species of flies; and the identification of 
the captured flies. Similarly a systematic testing of the various baits 
in different kinds of traps must be made, and the efficacy of poison 
bags as a means for attracting flies must be tested. The range of flight 
of flies from known breeding places must also be determined, and an 
investigation must be made of the enemies of adult flies—Bombex wasps 
and various other “ policeman flies,” as well as dipterous flies (asilid, 
&e.). ; 
In outlining further investigational work jn regard to the larval 
stages of the flies Professor Harvey Johnston placed first the import- 
ance of determining the breeding places (other than in wool, &¢., on 
living sheep) of the various species. This knowledge must. be of great 
value, of course, in the distribution’ of the chaleid parasites. Once the 
larva matures it becomes potentially an. enemy of the sheep. Following 
upon this-a careful study must be made of the biology of each of the 
‘species of flies which frequent sheep, especially the period eclapsing 
between the deposition of eges or larve by the female and the emer- 
gence of the adult fly. In the work already done it has been found 
that eyen on a well-kept property, where the number of sheep which 
escape observation is extremely small, sheep were being blown in the 
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