18 BULLETIN 408, U. S. DEPARTMENT OF AGRICULTUEE. 



practical larvicides; Berberis, Cincliona, and larkspur in the amounts 

 employed showed some larvicidal action. 



Various mixtures of calcium cyanamid, acid phosphate, kainit, 

 and gypsum were tested. 



One pound of calcium cyanamid in mixtures with 2 to 4 pounds of 

 acid phosphate proved effective in cages and boxes where the surface 

 exposure of the manure was approximately 4 square feet. 



A similar mixture may prove effective in pits. In both cases the 

 treatment should be based on the number of square feet of exposed 

 surface of the manure. The cost of this treatment, based on whole- 

 sale prices January 1, 1916, is approximately 1,4 cents per square foot. 



In several open-pile experiments calcium cyanamid applied in 

 mixtures with acid phosphate or kainit at the rate of one-half pound 

 per bushel of manure showed an apparent larvicidal action of 98 per 

 cent. By using a mixture composed of calcium cyanamid, acid 

 phosphate, and kainit, the three essential plant elements, nitrogen, 

 potash, and phosphoric acid, are added to the manure. The 

 nitrogen and ammonia which usually escape from untreated manure 

 piles will be retained if sufficient acid phosphate is used, and the 

 fly maggots will be killed at the same time. The cost of this treat- 

 ment, in which one-half pound of calcium cyanamid and one-half 

 pound of acid phosphate are applied for each bushel of manure, is 

 1.8 cents per bushel. 



SUMMARY OF THREE SEASONS' WORK. 



From the three seasons' work it appears that borax used at the 

 rate of two-thirds of a pound per 10 gallons of water and sprinkled 

 over 8 bushels of manure is the least expensive and the most effective 

 larvicide. Caution should be used in treating manure to be employed 

 for agricultural purposes, because of the injurious action on plant 

 growth of excessive applications of borax. It is, however, recom- 

 mended for the treatment of all manure not to be used for agricultural 

 purposes, for refuse piles of all kinds, stable floors, etc. The cost of 

 the borax treatment, when borax sells for 8 cents per pound, is one- 

 haK cent per bushel.^ 



Powdered hellebore, using one-haK pound per' 10 gallons of water, 

 and applying the same to 8 bushels of manure, is an effective larvicide 

 and without action on plant growth. The cost^ is variable. On 



1 It is unusually difficult to give a fair retail price for these substances because of the advance In 

 price of chemicals and fertilizers. Borax was quoted retail Washington, D. C. at 8J- to 12 cents per pound 

 in 100-pound lots; powdered hellebore, in 100-pound lots, at 35 cents per pound; acid phosphate SI. 75 to 

 S2for 167-pound sacks. Kainit is not obtainable at the present time; the usual price is S12 per ton, or 

 three-fourths to 1 cent per pound in 100-pound lots. Calcium cyanamid is manufactured by but one com- 

 pany in North America, although there are several companies producing it abroad. This American com- 

 pany does not ordinarily sell calcium cyanamid ia less than carload lots. The price was $51.45 per ton 

 f. o. b. Niagara Falls, Ontario. The figures just given were those quoted on March 1, 1916. Calcium 

 cyanamid is handled by manufacturers of mixed fertilizers. 



