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following results were obtained : — Ground hellebore, | lb. in 10 gals, of 

 water, 59 and 62 ; I lb. in 10 gals., 45 and 27 ; f lb. in 10 gala., 31 

 •And 42 ; J lb. in 10 gals., 16 and 49 ; aniline 1 in 200, 85 ; nitro- 

 benzene mixture, 89 and 81 ; pyridine 1 in 1,500, 8-3 and 47-6; in 

 another series of hellebore trials figures from 88'3 to 91*3 were obtained. 

 CVesylic acid and /3-naplithol had no larvicidal effect in cage experi- 

 ments ; para-dichiorobenzene about 16 per cent. ; formaldehyde, at 

 1 to 5, 1 to 8 and 1 to 10 dilutions of the commercial 40 per cent, 

 solution, onlv showed effect at 1 to 6 and then only 17 per cent. ; its 

 cost puts its use out of the question. In the nitrobenzene experiments 

 the quantity of fish-oil soap seemed to be important, the mixture 

 containing the largest quantity having the greatest effect. Oxalic 

 acid, 1 lb. and 2 lb. in 10 (U.S.) gals, of water, had no effect. The 

 variation of the eff'ect of pyridine between cage and open pile experi- 

 ments cannot be explained ; the cost is too high and the disagreeable 

 odour and toxicity of the substance make it objectionable. The use 

 of plants containing saponin was suggested to the authors by Dr. 

 Alsberg and the following were tried : — Corn cockle {Agrostemma 

 githago) ; wheat screenings containing about 43 per cent, of corn 

 cockle were used ; the results were variable, sometimes nil. sometimes 

 49 per cent. ; roots of Agave lecheguilla, 2| lb. in 10 gals, of water, gave 

 82 and 84 per cent. " Black Leaf 40 " showed no larvicidal action. 

 Ground seeds of larkspur {Delphinium), 1 lb. in 10 gallons with 

 1 per cent, sulphuric acid and allowed to extract for 12 hours, gave 

 figures varying from 57 to 90 per cent. Stramonium extract was not 

 satisfactory. Powdered hellebore proved the most efficient and 

 practical of all the substances tested, but as this is an actively poisonous 

 substance and farm poultry and animals peck at or consume manure, 

 tests were made with chickens for several weeks, freshly treated manure 

 being given every three days ; no ill effects were observed. The 

 comparative advantages of borax and hellebore are summarised as 

 follows : borax, which was shown in Bulletin No. 1 18 to be an effective 

 larvicide, is obtainable in all parts of the country, and the cost of 

 treating manure at the rate of 0-62 pound of borax per 8 bushels is 

 0-42 cents per bushel. Powdered hellebore, using one-half pound 

 to 10 gals, of water and applying this to 8 bushels of manure, is also 

 an effective larvicide and exerts no injurious action on the fertilising 

 value of the manure, as determined by bacteriological and chemical 

 analyses, and no injurious action on plants has been detected in any 

 of the field tests. Hellebore is used as an insecticide and is obtainable 

 in most cities and agricultural districts. The cost of this treatment 

 is 069 cents per bushel of manure. While borax may be applied 

 to manure at the foregoing rate and the treated manure may be added 

 to the soil at the rate of 15 tons to the acre without injuring vegetation, 

 excessive quantities may be used through carelessness, and injury to 

 vegetation may result. In the light of this year's experiments it 

 seems advisable to recommend borax as a larvicide for the treatment 

 of outhouses, refuse piles, and all other places where flies may deposit 

 eggs. On account, however, of the possible results of carelessness, 

 and as large quantities of manure are sometimes used by market 

 gardeners, it seems best to guard against possible injury to vegetation 

 by recommending powdered hellebore, since no injury can arise from 

 the use of excessive quantities, as it is entirely decomposed in the 

 course of the fermentation of the manure. 

 (C216) B 



