80 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 3 



]\Ir. George P. Weldon, field entomologist of the Experiment Station, 

 located at Delta, with instructions to use it in comparison with arse- 

 nate of lead. The arsenate of lead was being tested at 2, 3 and 4 

 pounds to each 100 gallons of water in one application only when the 

 petals were about nine-tenths off. 



The arsenious sulfid was used in two strengths to correspond with 

 the two stronger preparations of arsenate of lead in amount of metallic 

 arsenic contained. 



The applications were made by Mr. Weldon with a hand pump with 

 moderate force, but the treatment was thorough and in every way was 

 made as nearly like the lead arsenate sprays as possible. 



The results of the experiment as tabulated by Mr. Weldon are here 

 given : 



The trees sprayed Math 2 pounds of arsenate of lead to 100 gallons 

 of water averaged 94.7 per cent of their fruit free from all worm 

 injuries. The trees that were sprayed with 3 pounds to 100 gallons 

 bore fniit that was 95.5 per cent free from worm marks. Trees 

 sprayed with 4 pounds to 100 gallons bore fruit that gave exactly the 

 same percentage of worm marks as when 3 pounds were used. 



The trees sprayed with sulfid of arsenic had 93.6 per cent perfect 

 fruit upon trees sprayed with the weaker preparation, and 92.7 per- 

 fect from the trees where the stronger solution was used. 



The check trees average 58.9 per cent sound, or perfect, fruit, so 

 far as worm injuries were concerned. 



All of the experimental blocks, both sprayed and checks, were in 

 a large orchard, all of which was sprayed. Check trees in such a ease 

 benefit greatly by the spraying of surrounding trees and do not show 

 the contrast that they should with the results upon sprayed trees. 

 Two orchards in the same vicinity, one very poorly sprayed and one 

 not sprayed at all, bore apples that were 70 to 85 per cent wormy. 



So this test of sulfide of arsenic as a spray for the control of the 

 codling moth indicates that this poison may be as efficient for this 



I am convinced that a pure preparation of lime arseuite is not good to use. 



The solution probably contains the whole of the arsenic in combination 

 with sulfur. The lime-sulfur compound is easily decomposed by the carbonic 

 acid of the air, while the arsenious sulfid withstands the action of water, air 

 and carbonic acid very effectively. The sulfid of arsenics As,, S., contains 

 essentially 61 per cent of its weight of metallic arsenic, while lead arsenate 

 contains less than 10 per cent (9.87). 



The chief thing, however, is not that it may be placed on the market at 

 a lower price, but that it will remain longer in the soil in an insoluble form 

 than the compounds heretofore used. It is only a mitigation of the evil, 

 however, not a complete avoidance of it.— W. P. Headden. 



