24 
BULLETIN 278, U. S. DEPARTMENT OF AGRICULTURE. 
The homemade arsenate of calcium products, as noted previously, 
were low in arsenic oxid content, but as a whole proved relatively 
effective as poisoning agents. Formula (2), arsenic oxid 6.16 per 
cent, at the rate of 4 to 50, required 14 days, which was the same 
length of time required by formula (3), arsenic oxid 3.93 per cent, 
4 to 50, combined with lime-sulphur solution. The arsenate of cal- 
cium prepared along with self-boiled lime-sulphur killed all larvae in 
10 days. The experiment was closed at the end of 36 days, only 
one larva of the unsprayed lot having died. 
Experiment XIV. 
ARSENATE OF CALCIUM VERSUS ARSENATE OF LEAD, ALONE AND COMBINED WITH 
LIME-SULPHUR SOLUTION, AGAINST LARV.E OF THE FALL WEBWORM. 
Homemade arsenate of calcium was again tested in comparison 
with commercial arsenate of calcium (paste and powder) and arse- 
nate of lead, paste. These arsenicals were used alone and combined 
with lime-sulphur solution, 1J to 50. The results of this experiment 
will be found in Table XIV. 
Table XIV. — Tests of the hilling effect of various materials on the fall webworm. 
[Experiment started Aug. 27, 1914, Benton Harbor, Mich.; 10 larvae in each lot.] 
Lot 
No. 
Name and dilution. 
Dates of examination and number 
of larvae dying in each lot. 
Aug. 
31. 
September- 
10 14 16 19 
Total 
num- 
ber 
dead. 
Num. 
ber 
days re- 
quired 
to kill. 
Square 
inches 
foliage 
con- 
sumed. 
Arsenate of lead paste, 3-50 
do 
Arsenate of lead paste, 3-50+ lime-sul- 
phur, 1J-50 
do 
Arsenate of lead paste, 5-50 
do 
Arsenate of lead paste, 5-50+ lime-sul- 
phur, 1^-50 
do 
Arsenate of calcium, commercial paste, 
5-50 
do 
Arsenate of calcium, commercial paste, 
5-50+lime-sulphur, l£-50 , 
do 
Arsenate of calcium, commercial pow- 
der, 2^-50 
.....do 
Arsenate of calcium, commercial pow- 
der, 2J-50+lime-su]phur, 1^-50 
do 
Arsenate of calcium (homemade paste, 
formula 1), 5-50 
do 
Arsenate of calcium (homemade paste, 
formula 1), 5-50+lime-sulphur, 1^-50. 
do 
Arsenate of calcium (homemade paste, 
formula 3 ) , 5-50 
.do. 
Arsenate of calcium (homemade paste, 
formula 3), 5-50+lime-sulphur, 1^-50 
do 
Lime-sulphur, 1^-50 
do 
Check (unsprayed) 
do 
5 
10 
18 
10 
20 
3 

10 
18 
10 
14 
10 
20 
10 
14 
1 
5 
3.00 
3.00 
2.25 
.25 
2.50 
3.50 
.50 
1.50 
63.00 
38.00 
13.50 
3.75 
10.50 
20.05 
4.00 
1.75 
42.00 
27.50 
9.25 
10.00 
63.00 
72.25 
19.50 
17.00 
8.00 
1.25 
81.00 
69.25 
