THE HOUSE FLY. 17 



morphine, and cocaine may be mentioned as examples, which act very 

 intensely on the animal body. For the treatment of manure a water 

 extract of the hellebore is prepared by adding h pomid of the powder 

 to every 10 gallons of water, and after stirring it is allowed to stand 

 24 hom^. The stock mixtm-e thus prepared is sprmkled over the 

 manure at the rate of 10 gallons to every 8 bushels (10 cubic feet) 

 of manm-e. From the result of 12 experiments with manure piles 

 treated mider natural conditions it appears that such treatment 

 results in the destruction of from 88 to 99 per cent of the fly larvae. 

 Amounts of hellebore less than ^ pound to every 8 bushels of manure 

 are not so effective, while stronger applications, of course, will give 

 somewhat better results. 



Bacteriological studies of the treated piles proved that the bacteria 

 were not injured or their development retarded, and chemical analy- 

 sis showed that the composition of the manure was unaltered. Fur- 

 thermore, several field tests were made in growuig cabbages, turnips, 

 lettuce, potatoes, wheat, and a few other crops on plats which had 

 been fertilized with hellebore-treated manure, with the result that 

 there appeared no injury whatever that could be ascribed to the use 

 of this substance. The only possible objection to the use of hellebore 

 seems to be the possibility of poisoning farm animals, as might 

 happen if, for example, the barrel or tank in which the stock solution 

 was prepared were left uncovered in an accessible place. It is quite 

 safe to say that chickens will not be injured by pecking at hellebore- 

 treated manure. This has been tested carefully. Hellebore can be 

 obtained both in ground and powdered form, but the powdered form 

 gives the best results in the destruction of fly larvae. 



TREATMENT WITH POWDERED BORAX. 



Another chemical found to be even more effective as a larvicide is 

 powdered borax. This is an morganic substance, available in com- 

 mercial form in all parts of the country. It has the advantage of 

 being comparatively nontoxic and noninflammable and is easily 

 transported and handled. The mmimum amount necessary to kdl fly 

 larvae was found to be 0.62 pound per 8 bushels of manure, or about 

 1 pound per 16 cubic feet. Best results were obtained when the 

 borax was applied in solution, or when water was sprmkled on after 

 the borax had been scattered evenly over the pile. Borax is not only 

 effective in kOling the larvae, but when it comes in contact with the 

 eggs it exerts a toxic action which prevents them from hatching. 

 When applied at the rate of 1 pound to 16 cubic feet it was found to 

 kUl about 90 per cent of the larvae, heavier applications killing from 

 98 to 99 per cent. 



