20 
BULLETIN 278, U. S. DEPARTMENT OF AGRICULTURE. 
Other arsenicals, namely, commercial arsenite of zinc and commercial 
arsenate of calcium, were likewise tested. The results are given in 
Table XI. 
Table XI. — Tests of the killing effect of various materials on the fall webuorm. 
[Experiment started July 17, 1914, Benton Harbor, Mich.; 10 larvae in each lot.] 
* 
Name and dilution. 
Dates of exami- 
nation and num- 
ber of larvae 
dying in each lot. 
<3 
o 
Xi 
u 
m 
£ 
a 
© 
T3 
"3 
©< 
£ . 
•o o 
St*" 1 
* 
B 
1 
© e 
d 
o 
h3 
July. 
August. 
2 3 
03 O 
23 
29 
7 
13 
?. 
1 
Kerosene emulsion, 10 per cent 

10 
10 

110 
no 
10 




10 
10 
10 
10 
10 
10 
10 
10 

...... 
6 
27 
6 
6 
6 
6 
6 
61.00 
?, 
Arsenate of lead powder, 1^-50 + kerosene p-mulsion, lOper'cent. 
Arsenite of zinc powder, l§-50-j- kerosene emusion, 10 per cent. 
Arsenate of calcium, commercial powder, 1J— 50+ kerosene 
emulsion, 10 per cent 
0.36 
3 
0.20 
4 
3 
6 
1 
13.50 
s 
0.01 
6 
Arsenate of lead powder, 1J— 50+ anthracene emulsion, 10 per 
0.01 
7 
0.14 
8 
Arsenite of zinc powder, l|-50 
10 
10 

0.04 
9 
Arsenate of calcium, commercial powder, 1 J-50 
0.48 
10 
Check (unsprayed) * 



53. 00 
i Foliage badly burned— unfit for consumption. 
Kerosene emulsion alone, at a 10 per cent strength, had no poison- 
ous effect upon the fall webworm larvae — at least none had been 
killed after having fed for a period of 27 days, with a consumption 
of 61 square inches of foliage. The arsenate of lead alone killed the 
10 larvae in 6 days — foliage consumed, 0.14 square inch. A com- 
bination of these insecticides also caused the death of all the larvae 
in 6 days after 0.36 square inch of foliage had been eaten. The 
other arsenicals, alone or combined with the emulsion (except arse- 
nate of calcium combined), likewise killed in 6 days after a relatively 
small amount of foliage had been consumed. Arsenate of calcium 
powder, used alone, was quite as effective as the other arsenicals, but 
in combination with the emulsion 27 days were required to kill the 
larvae, which consumed 13.50 square inches of foliage. A similar re- 
sult was obtained in a later experiment. (See Experiment XIII.) 
Anthracene emulsion, 10 per cent, alone and combined with arsenate 
of lead, burned the foliage badly, rendering it unpalatable. 
As shown in Experiment XV, kerosene emulsion, 10 per cent, com- 
bined with arsenate of lead is also an effective aphidicide. Although 
there is some breaking down of the materials in combination, no 
injury to the foliage was noted in the laboratory tests. 
