182 The Effect of Various Chemicals on Blow-Fly 



Summary. 



In conclusion, the preliminary character of our experiments may 

 again be emphasised. Final conclusions as to the insecticidal value of 

 any preparation can never be drawn, at least with any degree of satis- 

 faction, from laboratory experiments alone. These should obviously 

 be followed by field work under natural conditions, which unfortunately 

 is not possible in this country. 



The general results, which we summarise below, are intended 

 therefore to afford some indication as to possible lines upon which 

 future field work might profitably be pursued, rather than as definite 

 recommendations of substances, by the employment of which the 

 Blow-fly Pest may be controlled. 



Of substances repellent to the Blow-fly, and therefore capable of 

 protecting sheep from their ravages, the following appear to be the 

 most suitable: methyl salicylate, jo-nitraniline, picric acid, creosote, 

 green oil, boracic acid, fusel oil, pine oil, alizarine oil, origanum oil, 

 mustard oil, sod oil, iodoform, dimethylaniline, quinoline, allyl alcohol, 

 aloin, saponin, copper carbonate, nitrobenzene, sinapis oil and aniseed 

 oil. 



For the application of toxic agents, a powder form has been found 

 to be very convenient and efficient, precipitated chalk forming a suitable 

 and cheap basis. The substances, applied in this form, which appear 

 to be most toxic to the Blow-fly larva, comprise the following : arsenic 

 sulphide, nitrobenzene, eucalyptus oil, methyl salicylate, cedarwood 

 oil, ^-nitraniline, /3-naphthylamine, oxalic acid, borax, quinoline, ally] 

 alcohol, picric acid, dimethylaniline, copper carbonate, oil of cloves, 

 turpentine, /3-naphthol, creosote, fusel oil, sinapis oil, aniseed oil and 

 iodoform. Since the young larvae are much more susceptible than 

 the old, in field work, the medicated powder should be applied either 

 previous to, or in the very earliest days of, the larval stage. 



Various vapours have been shown to be toxic to the Blow-fly larvae, 

 and of these the most successful are brombenzene, chloral hydrate, 

 ethyl acetate, iodine and pyridine. 



