16 



BULLETIN 118, U. S. DEPARTMENT OF AGRICULTURE. 



other. The control cages showed 1,508 and 1,287 fljes. The gas 

 liquor in the 1-5 strength was strongly bactericidal, reducing the 

 number of bacteria as shown in the control from 6,130 million to 

 92.8 million. In view of the fact that the gas liquor showed a bacte- 

 ricidal action and that the transportation of a liquid in large amounts 

 is expensive, it was not studied further, although it possesses certain 

 advantages, as it contains a considerable amount of nitrogen, practi- 

 cally all of which is in the form of ammonia. This nitrogen is, 

 however, all in soluble and volatile form and easily lost. 



CALCIUM CYANAMID. 



The treatment with calcium cyanamid was tried at the suggestion 

 of Dr. Alsberg. It has been used in cage experiments at Arlington. 

 Va., and the results obtained are recorded in Table III. 



Table III. — Destruction of fly larva- in horse manure— Larvicidal results with 

 calcium cyanamid — Cage experiments at Arlington, Va., summer of 1913. 



No. 



Series F: 



1 



2 



3 



4 



Series G : 



1 



2 



3 



Treatment of 8 bushels of manure with 10 gal- 

 lons of water. 



Calcium cyanamid, 20 pounds. 

 Calcium cyanamid, 5*pounds . . 



Control . . *. : 



....do 



Calcium cyanamid, 5 pounds. 

 Calcium cyanamid, 4 pounds. 

 Calcium cyanamid, 3 pounds. 



Control . . '. 



....do 



Larval mor- 

 tality, 1 quart 

 sample of ma- 

 nure 2 days 

 after treat- 

 ment. 



Alive. Dead 



Flies 



Larvae 



emerged. 



killed. 





Per 



Number. 



cent 



7 



99.5 



52 



96.3 



1,508 







1,287 







92 



20.0 



761 





56 



51.3 



25 







204 







Larvse 



in drip 



pan. 



Num- 

 ber. 



12 



400 



The calcium cyanamid was scattered over the manure in powdered 

 form and in all cases water was added. From the table it appears 

 that the 20-pound application killed over 99 per cent of the larvae. 

 The 5-pound applications gave varying results, as seen in the table, 

 and in one cage experiment not shown 58 per cent of the larvae were 

 destroyed. This gives an average larvicidal power of 58 per cent for 

 this amount of the calcium cyanamid. In one cage ttst not shown 

 where 4 pounds were applied, 40 per cent were killed, but in the cage 

 experiment given in Table III no larvicidal action was apparent. 

 Since calcium cyanamid is used to some extent as a fertilizer and is 

 a means of adding nitrogen to the manure, and thus to the soil, it is 

 highly desirable that a further study of this chemical be made, not 

 only to determine more exactly its larvicidal action, but also to de- 



