164 



March 1917. The destruction of all carrion, offal, and animal matter 

 which serves as the primary breeding gromids of the sheep-fly, to 

 which reference has already been made [see this Review, Ser. B, iii; 

 pp. 13-17, 184], has come to be regarded as of such primary importance 

 that many sheep owners are in favour of compulsory legislation on 

 the subject. 



The best method of destroying dead sheep, namely by burning, is 

 often impossible o\vdng to shortage of labour, to the danger of fire in 

 summer time, and to the lack of lire- wood on the plains. Under these 

 circumstances they can be utilised as poison-baits to kill large numbers 

 of the active blow-flies always hovering round a carcase. The dead 

 animal should be half skinned, disembowelled, the paunch slit and 

 the contents scattered about, the exposed flesh slashed with a knife 

 and the whole sprayed or covered ^^'ith arsenic water. This remains 

 attractive until the second day, by which time the arsenic will have 

 rendered the flesh dry and hard. If the carcase be then turned over 

 and the operation repeated, many more flies will be destroyed and 

 the remains will then simply dry up. 



To make the arsenic water for sprajdng, 1 lb. white arsenic (or 

 arsenious oxide) should be mixed with 1| lb. washing soda and the 

 whole dissolved by boiling in 5 gals, water. Before use this must be 

 diluted with another 5 gals, water. The solution may be more easily 

 made by using sodium arsenite, which is readily soluble, \\ lb. being 

 used in place of 1 lb. white arsenic. A dead horse or bullock in a 

 sheep paddock cannot be dealt with by burning or burying, as it 

 would entail too much fuel, time and labour, but can be treated by 

 driving four stakes into the ground round the carcase and comiecting 

 them with a strand of fencing wire 2 or 3 ft. above the ground. A 

 Hessian cover is then thrown over the vv^re and the lower edges are 

 pegged to the ground, a bank of earth being then thrown over them. 

 The maggots in the carcase hatch out in about a fortnight, and the 

 flies, being unable to escape, die in large numbers. All butcher's 

 ofial should be burned, an incinerator being easily made vnih. a few 

 mud bricks and half a dozen fire-bars raised a foot or two oS the 

 ground to create a draught. Freshly-flayed skins should be treated 

 with arsenic water to kill flies and protect them from beetles. 



Statements have frequently been made that blow-flies breed in 

 decajdng vegetable matter along river banks and the margins of 

 lagoons, but up to the present no specimens of blow-fly maggots ha^ve 

 been taken in vegetable matter. The maggots found were j^robably 

 those of the black bush-fly, Musca autumnalis (corvina), the common 

 house-fly, Musca doniestica, or of a small white-barred fly which 

 swarms along the edges of swamps. 



Experiments carried on with a view to finding attractive substances 

 combining both fermentative and putrefactive processes, the resultant 

 products of which would form a mixture resembling putrefying offal 

 in odour, have resulted in the production of two such mixtures. At 

 comparativel)^ small cost these can be easily distributed in suitable 

 vessels which can be frequently emptied and refilled. The most 

 important point is that both sexes of all the different species of blow- 

 flies should be attracted, which is not the case with baits of essential 

 oils, each of which attracts the males of one species only. The two new 

 mixtures are, caseinogen, prepared from fresh or skimmed milk, 



