SCIENCE AND INDUSTRY. 
cleanest paddocks. The periods referred to must be determined for 
the various months and seasons of the year, and the work involves the 
collection of certain climatological data. When the distinctive charac- 
ters of the various larve have been worked out, Professor Harvey 
Johnston considers that it should then be possible to determine what 
flies are attracted to the poison’ bags in order to deposit larvae. Fur- 
ther information has yet to be obtained regarding the use of various 
chaleids against larve and pups, and also what other organisms destroy 
fly larve. 
Both in Queensland rant in New South Wales a great deal of work 
has been done in investigating the parasiticism of various chalcid flies, 
and the results obtained suggest that several natural enemies of the 
blow-flies will, in the near future, by means of systematic breeding 
and liberation, play a very important part in the suppression of the 
blow-fly pest. Professor Harvey Johnston’s scheme provides for the 
breeding out of pup of flies from various localities in the district 
(and from other districts, if possible) to ascertain the percentage of 
pupx naturally infected ‘with one or other of the ‘chaleids during 
various periods of the year. Hand-in-hand with this work will be 
carried out a careful study of the biology of the chaleid fly parasites 
already known in Queensland, in order to determine the best time. for 
their liberation, and the introduction of the other chalcids known to 
occur in New South Wales as enemies of the flies. 
Experiments are now in progress in Queensland with a view to 
determining the relative values of the various sheep dips, either sepa- 
rately or in conjunction with varying qualities of other known chemical 
poisons, the object being to discover the best specific for preventing the 
various kinds of sheep from fly attack, e.g., weaners, lambing ewes, 
wethers, &¢. Jetting, dipping, showering, have been’ tried, and the 
‘results have been made known to pastoralists. The treatment of blown 
sheep by using various dressings to destroy larve already present dn 
sheep or in the wool, also to ascertain the influence of the medicaments 
in preventing re-infestation, has also been carried out. This branch 
of the investigations will be continued, and biological work in con- 
nexion with these experiments will be undertaken. 
Another important phase of the experimental work will be the 
investigation of the acute affection of sheep sometimes associated with 
fly infestation. The problems to be determined in this connexion are-— 
(a) Under what conditions does it occur? (6). Its nature—is it a sep- 
ticemia? (c) How transmitted? and (d) the possibility of making a 
vaccine and using it (1) in affected sheep, and (2) as a means of pro- 
tecting other sheep against affection. 
ENR. 
430 
