HOUSE-FLY INVESTIGATIONS. 479 



The treatments began with the series of vapourisable liquids 

 which led to the surface applications. Although these treatments 

 are more satisfactory than any hitherto recommended, it is 

 admitted that there are still some doubtful points in connection 

 with the relation of the migration of the larvae to the condition 

 of the manure due to chemical action other than changes in 

 temperatvire. For the early expei'iments infected manure was 

 not obtainable ; maggots enclosed in gauze were placed in 

 different positions in the stacks. W'hen House-flies became 

 abundant naturally infected manure was used. 



The Tar-oil treatment is recommended for large accumulations 

 of manure, either in military camps or for horticultural purposes, 

 in the proportion of one part of oil to forty parts of soil. One 

 gallon of liquid mixed with forty gallons of soil covers 100 square 

 feet. The oils are products of the first distillation of tar. For 

 large quantities the price is Is. per gallon, making the cost of the 

 treatment Id. per cubic yard for surface treatment only and '2d. 

 per cubic yard for treatment of the ground and of the surface. 



The value of manure is Is. 9d. the cubic yard. 



Treat the manure which is added to a heap every five days, 

 and if fresh ground is to be covered, when adding to a heap, oil 

 the ground first. 



Maggots present in manure which is stacked on soil dressed 

 with a Tar oil cannot escape into the ground to pupate. The 

 manure ferments normally when treated with the oil, and the 

 maggots perish in the treated soil to which they are driven, or 

 they pupate in a stack which is cool (Experiment III.). That 

 a manure-stack treated with Green oil or with Neutral Blast- 

 furnace oil will remain immune to fly-attack has been confirmed 

 by Experiments II., IV., V., VI., and VII., where in each case 

 the Control became infected. 



That the treatment is harmless to plants is shown by the 

 results of Plant Trial I. (Plots) and III. (Pots) and Messrs. 

 Sutton's Series II., Ac and Cc. 



The vapour treatment with Tetrachlorethane, in the miscible 

 or in the pui'e form, is recommended for small quantities of 

 manure and for fresh manure used for hot-beds in the strength 

 of 2 ozs. to 10 cubic feet of manure. 



Tetrachlorethane is a heavy liquid, specific gravity 1-6 audi 

 boiling-point 147° 0. It is non-inflammable and commercially 

 available. The price of pure Tetrachlorethane is 35s. per cwt. 

 and that of Westoran 52s. per cwt. That a manure-stack treated 

 with Tetrachlorethane will effectively kill maggots has been 

 proved by Experiments I., II., and III., and tliat used with 

 manure at 2 ozs. per 10 cubic feet is safe for plants, by Ti-ials 3 

 (Frames) and Messrs. Sutton's Series I., Ea. 



It is worth noting that all the treatments have been tested in 

 intensive culture with satisfactpry results at the strengths. recom- 

 mended. 



