28 BULLETIN 278 ; U. S. DEPARTMENT OF AGRICULTURE. 
Experiment XVI. 
FIELD TESTS OF ARSENATE OF CALCIUM VERSUS ARSENATE OF LEAD AGAINST THE COD- 
LING MOTH, 1914. 
One of the most promising of the insecticides tested during the 
season of 1914 was an arsenate of calcium paste. A commercial 
article was employed at the rate of 2 pounds to each 50 gallons of 
lime-sulphur solution. The plat sprayed with this material consisted 
of 12 trees, the fruit from five of which was examined throughout the 
season. The plat sprayed with arsenate of lead paste, 2 pounds com- 
bined with 50 gallons lime-sulphur solution, included 12 trees, the 
fruit from six of which was examined. Plats III, IV, and V, located 
in different parts of the orchard, were left unsprayed as a check. 
These plats had a total of eight trees, all of which were examined. 
Three applications were given Plats I and II, for the control of the 
codling moth: (1) When petals dropped; (2) three to four weeks 
later; (3) nine weeks after petals dropped, for the control of the sec- 
ond brood. 
The arsenate of calcium paste was analyzed by the Bureau of 
Chemistry, United States Department of Agriculture, as follows: 
Analysis of arsenate of calcium (paste) . 
Per cent. 
Moisture 55. 80 
Total arsenic oxid, As 2 5 18. 82 
Total calcium oxid, CaO 17. 93 
Total lead oxid, PbO 3. 72 
Soluble impurities, exclusive of PbO and As 2 5 1. 84 
Water of constitution and undetermined (small amount of C0 2 ) 1. 89 
Total 100. 00 
Soluble arsenic Trace. 
This sample contains lead equivalent to approximately 5.5 per cent 
lead arsenate. The results of this experiment are shown in Table 
XVI. 
Table XVI. — Sound and wormy apples from sprayed and unsprayed plats. 
[Poison test. A comparison of arsenate of calcium with arsenate of lead. Benton Harbor, Mich., 1914.] 
Plat 
Treatment. 
Tree 
No. 
Condition of fruit. 
num- 
ber. 
Wormy. 
Sound. 
Total. 
Per cent 
sound. 
I 
Arsenate of calcium (commercial paste) , 2 pounds 
to 50 gallons lime-sulphur solution. 
Plat total 
1 
2 
3 
4 
5 
123 
78 
47 
44 
63 
8,087 
5,424 
4,988 
6,132 
4,283 
8,210 
5,502 
5,035 
6,176 
4,346 
98.50 
98.58 
99.06 
99.43 
98.56 
355 
28,914 
29,269 
98.79 
