185 



XV. APPENDIX C. 

 PREVENTIVE MEASURES. 



In 1897 Howard conducted a series of experiments with a 

 view to discovering an insecticidal substance which could be 

 used for the destruction of the larvae in the heaps of manure 

 in which they were breeding. He found that both lime and 

 gas lime were not efficacious. In an experiment in which 

 8 Ibs. of horse manure containing larvae were treated with a 

 pint of kerosene, which was washed down into the manure 

 with water, it was found that all the larva? were killed. He 

 also found that by treating 8 Ibs. of well-infested horse 

 manure with one pound of chloride of lime all the larva? 

 were killed, but the results were not satisfactory when a 

 quarter of the quantity of chloride of lime was used. On 

 experimenting with the kerosene treatment on a large scale 

 he found that it was not only laborious but also not entirely 

 successful, as is sometimes the case in the practical applica- 

 tion on a large scale of successful experimental methods. He 

 therefore devised another method of treating the horse 

 manure of stables. A chamber six feet by eight feet was 

 built in the corner of the stable with which it communicated 

 by means of a door; it was provided also with a window 

 furnished with a wire screen. The manure was thrown into 

 the chamber every morning and a small shovelful of chloride 

 of lime scattered over it. At the end of ten days or a 

 fortnight the manure was removed through an open door 

 and carted away. The experiment was carried out in the 

 stable of the U.S. Department of Agriculture and a marked 

 decrease in the number of flies was observed. 



In France residuum oil has been proposed as a suitable 

 substance for the destruction of the eggs and larva? in privies 

 and cesspools. Of such insecticidal substances as have been 

 practically tested chloride of lime is undoubtedly the cheapest 

 and most efficacious. The best preventive measure, however, 



