MISCELLANEOUS IXSECTTCIDK 1 N V INSTIGATIONS. 
15 
used at the weaker strengths, apparently had no effect on the larvae. 
The arsenate of lead killed all the larva; in 4 days. 
For the Datana ministra, the commercial lead chromate was used 
at the rate of 8 pounds to 50 gallons of water, and at this strength 
the killing effect of the material compared favorably with that of 
arsenate of lead, 2 pounds to 50 gallons. The lead chromate, home- 
made, was used at three strengths — f, 1J, and 3 pounds to 50 
gallons of water. The weakest strength killed all the larvae in 6 
days, the next stronger in 5 days. Only one larva had died in the 
unsprayed lot at the time the experiment was closed, August 14. 
Experiment VIII. 
COMPARISON OF THE KILLING EFFECT OF ARSENATE OF LEAD, ARSENATE OF CALCIUM, 
ARSENATE OF ZINC, ARSENITE OF ZINC, AND LEAD CHROMATE ON LARV.E OF THE 
FALL WEBWORM. 
Different forms of arsenate of lead, arsenate of calcium, and lead 
chromate were tested against the larvae of the fall webworm (lly- 
j)hantria cunea). Arsenate of zinc and arsenite of zinc were also 
included in this test, as shown in Table VIII. 
Table VIII. — Tests of the killing effect of various materials on the fall webworm. 
[Experiment started July 23, 1913, Benton Harbor, Mich.; 20 larvse in each lot.] 
Name and dilution. 
Dates of examination and number of larva? dying 
in each lot. 
o 
a> 
£ 
3 
a 
o 
20 
a* 
T3 O 
it, 
3 O 1 
l-d 
|| 
,pH o 
d 
o 
•J 
July. 
August. 
24 
25 
26 
27 
28 
29 
30 
31 
1 
2 
3 
4 
0Q 
1 
Arsenate of lead paste, corn- 























1 




1 
1 






1 
1 







1 

2 
1 
2 

1 

1 
2 
1 


2 








1 

2 
1 
1 
2 
3 
2 
2 
1 
1 
7 
2 






4 
10 
4 
10 
6 
10 
5 
11 
15 
12 
12 
18 
16 
3 
8 
1 

1 



9 
6 
9 
4 
9 
1 
3 
2 
1 
2 
3 
1 
3 
2 
5 
9 
5 
6 
4 


1 
2 
6 
8 
8 
6 
(> 
6 

8 
8 
8 
11 
10 
12 
0.42 
2 
do 
20 
.24 
3 
Arsenate of lead powder; 
commercial (1), 1-50 
. do... 
20 
20 
20 
20 
20 
20 
20 
20 
20 
20 
20 
20 
20 
20 
20 
20 
20 
20 
3 
1 
.41 
4 
.22 
5 
Arsenate of lead powder, 
commercial (2), 1-50 
do 
.13 
6 
2 
5 
5 
.24 
7 
Arsenate of calcium paste, 
2 
3 
.75 
g 
do 
. ss 
9 
Arsenate of calcium, home- 
.15 
10 
.17 
11 
Arsenate of calcium, home- 
made (2) , T 8 -50 
2 
2 
.19 
1? 
...do 
.12 
13 
Arsenate of zinc, homemade, 
• 50 
.29 
14 
.20 
15 
Arsenite of zinc powder, 
4 
1 
8 
8 
6 


1 
3 
2 
1 
1 
1 

.50 
10 
. do. . 
.79 
17 
Lead chromate powder, 
.84 
18 
do 
1 
2 
3 


1 
2 
4 


1 
2.01 
19 
Lead chromate, homemade, 
l£-50 
1.70 
?0 
.....do 
1 
2 
1 
1 


2.09 
?1 
20 17 
22 
do 
20.56 
