Insects and Parasitic Diseases- IS 



In starting an experiment the. jar is two-thirds filled with previ- 

 ously sterilized and cooled horse faeces, and the clip fixed in posi- 

 tion, whilst the flies are caught in the vicinity of the stables in an 

 ordinary butterfly net, with the end of the bag secured by a short 

 piece of twine instead of the usual permanent stitching. As soon as 

 a sufficient number of flies of the required species are caught, they 

 are forced to the extreme end of the net by a few rapid sweeps, and 

 imprisoned there by a few twists of the bag behind them, the twine 

 is then untied, and the end of the net inserted well into the open 

 end and towards one side of the otherwise closed gauze cage, which is. 

 then slipped over the mouth of the jar and forced down until its 

 lower edge rests firmly in the metal clip. In a few minutes the 

 flies find their way out of the open end of the net and congregate at 

 the top of the cage. The cage is then tipped up sufficiently to 

 permit of the withdrawal of the net and again forced down until it 

 rests in the clip, the free ends of which are pressed firmly against the 

 sides of the jar to hold the cage in position. 



The best results were obtained when the flies were fed soon after 

 being placed in captivity. For this purpose blood, sugar and water, 

 cow's milk, and a preparation of dried separated milk, with the 

 addition of water, were tried. The latter being readily obtainable 

 at all times, and easily prepared, was found to be the most satis- 

 factory. The liquid food was conveyed to the strip of tin across- 

 the mouth of the jar by means of a pipette passed through the 

 meshes, the cage was then placed in the sunlight, or, in dull 

 weather, near an electric radiator. 



As a rule, sufficient eggs were deposited during the first day of 

 confinement; if not, the flies were again fed and left for another 

 day. When sufficient eggs were secured, the flies were liberated 

 or removed in the gauze cage to another similar breeding jar, and 

 the first jar covered with paper retained in position by means of 

 a rubber band., 



No special precautions were taken to maintain the eggs and 

 larvae at a uniform temperature except that, as a rule, during 

 the winter months they were kept in an improvised incubator, or 

 near the electric radiator, at a temperature ranging from 20°C. 

 to 28°C. During the summer months artificial heating was not 

 resorted to. 



On alternate days the larvae were supplied with freshly sterilized 

 faeces, sometimes added to the top of the earlier supply, but more 

 often placed in a clean jar. In the latter case the larvae were 

 separated from the old faeces by merely turning the first jar into 



