April, '15] 



SCOTT: ARSENATE OF LIME 



197 



of lime on peach trees as a foliage test and found that at a dilution of 

 1| pounds (16 per cent arsenic oxide) to 50 gallons of water it almost 

 defoliated the trees. Arsenate of lead used on the same variety caused 

 very little injury, although this arsenical has been known to seriously 

 injure peach foliage under certain weather conditions. It is evident 

 from this test that arsenate of lime is more likely to injure susceptible 

 foliage than arsenate of lead. 



It appears from the results of these various experiments that for 

 spraying apple and shade trees arsenate of lime may be used with 

 the same degree of efficiency and safety as arsenate of lead. The 

 chief advantage it has is in the matter of cost, being cheaper than arse- 

 nate of lead. It mixes with lime-sulphur solution without causing 

 any chemical reaction which fact might be considered as another 

 advantage, neither material being decomposed by the combination. 

 Unless some unsuspected objection to this new insecticide develops, 

 it would seem a waste of money to continue the use of the more expen- 

 sive poison. 



AIe. Glenn W. Herrick: I would like to ask how much this 

 poison can be sold for? 



Mr. W. AI. Scott: I cannot answer that question definitely 

 except that there ought to be about the same difference in the cost 

 of arsenate of lime and arsenate of lead as there is in the cost of the 

 lead and the lime used in their preparation, although I have no figures 

 on the cost of manufacture. It is perhaps needless to remark that 

 this paper is not given for advertising purposes because arsenate of 

 lime can be made by anyone; in fact the fruit-grower can make it in 

 his orchard. 



Secretary A. F. Burgess: Last spring we secured a barrel or 

 two of arsenate of lime and several areas were treated by Mr. Worth- 

 ley's men. 1 would like to ask him to make a statement in regard to 

 the amount of poison used and the general results of the spraying. 



AIr. L. H. Worthley: We used about two hundred pounds of 

 poison at the rate of 10 pounds to 100 gallons of water. The results 

 from the standpoint of destroying caterpillars was as good as when 

 arsenate of lead was used, but considerable burning resulted to some 

 of the trees, especially cherry, apple, oak, maple; although almost 

 every species treated showed some burning. 



AIr. a. L. Quaintance: Mr. Siegler of the Bureau of Entomology 

 has been working with arsenate of lime, especially as to its home 

 preparation, and I shall be glad if he will state briefly some of the 

 results. 



AIr. E. H. Siegler: We have been using arsenate of lime in various 



