156 
Journal of Agricultural Research 
Vol. XXIX, No. 3 
SPRAYING AND DIPPING TESTS FOR THE 
CONTROL OF LARVAE WITH ARSENATE 
OF LEAD 
Further tests were then conducted to 
determine the effectiveness of spraying 
plants with arsenate of lead, or dipping 
them in this arsenical, for the control 
of partially grown larvae. The results 
of these experiments are given in Table 
XII. 
DUSTING TESTS FOR THE CONTROL OF 
LARVAE 
The results obtained by dusting 
with the arsenical-sulphur mixtures, as 
shown in Table XIII, were gratifying 
and hardly need further comment, ex¬ 
cept the statement that in the earlier 
cumbing to this insecticide. The lar¬ 
vae, after feeding on the dusted foliage, 
soon lose their normal greenish color, 
becoming sluggish and limp. After 
death their bodies are rather soft and 
have a sickly yellowish color. 
Results of these tests show a definite 
control, indicating that timely spraying 
with or dipping in arsenate of lead is 
effective in killing the larvae. 
DUSTING TESTS FOR THE CONTROL OF 
THE MOTHS 
During the spring of 1924, in pre¬ 
liminary experiments, nicotine dusts 
containing 5 per cent of nicotine sul¬ 
phate (2 per cent pure nicotine) 
proved effective in killing the moths. 
Table XIII .—Control of larvae of Phlyctaenia rubigalis by dusting 
Total 
Num- 
Experi¬ 
ment 
Date 
Plant 
Treatment 
num¬ 
ber of 
ber of 
dead 
Date of 
death 
Observations and 
results 
larvae 
larvae 
1921 
I__. 
Apr. 8 
Cineraria... 
Lead arsenate, 10 per 
cent; sulphur, 90 
per cent. 
58 
26 
Apr. 9 
Apr. 11 
Apr. 12 
Apr. 16 
|42 dead larvae; 6 alive; 
> 10 disappeared; 72 
1 per cent kill. 
13 
1 
2 
II_ 
Apr. 8 
Marguerite. 
Same as Experiment 
. I. 
13 
1 
Apr. 9 
1 larva dead; 11 dis- 
appeared; 1 pupated. 
III_ 
May 13 
Calendula.. 
.. .do_ __ 
23 
17 
May 14 
May 17 
17 dead; 5 disappeared; 
1 alive; 74 per cent kill. 
IV. 
May 16 
...do_ 
_do_ 
19 
3 
May 17 
May 18 
8 
May 23: 100 per cent 
6 
May 19 
' kill. 
2 
May 23 
V_. 
May 16 
.do_ 
Calcium arsenate, 10 
per cent; sulphur, 
41 
6 
May 17 
May 18 
40 larvae dead within 
16 
1 week; 1 pupated 
90 per cent. 
5 
May 19 
(plants treated 3 
5 
May 20 
days before larvae 
7 
1 
May 23 
May 24 
were due to pupate); 
97 per cent kill. 
[100 per cent kill; larvae 
VI_ 
May 12 
Marguerite. 
Lead arsenate, 15 per 
36 
32 
May 13 
1 week old; all dead 
cent; sulphur, 85 
4 
May 14 
within 40 hours after 
per cent. 
dusting. 
VII_ 
May 12 
_do. 
Same as Experiment 
VI. 
23 
20 
3 
May 13 
May 14 
j 100 per cent kill. 
VIII..., 
May 13 
Calendula- 
Lead arsenate, 20 per 
25 
20 
May 14 
May 14, 20 larvae l 
cent; sulphur, 80 
per cent. 
week old killed; 4 
alive but later dis¬ 
appeared; 80 per cent 
kill. 
IX_ 
May 16 
.do_ 
Same as Experiment 
13 
6 
May 17 
VIII. 
1 
5 
May 18 
May 19 
100 per cent kill. 
1 
May 20 
X_ 
May 12 
.do. 
Lead arsenate, 10 per 
cent ;tobacco dust, 
10 per cent; sulphur, 
35 
26 
May 13 
May 14 
May 16 
35 larvae 2 weeks old 
■ killed; 100 per cent 
kill. 
3 
3 
80 per cent. 
3 
May 17 
tests a few individuals crawled away 
from the treated plants anid were lost, 
because the plants were not confined 
within cages. Without exception, how¬ 
ever, when such specimens were located 
they were dead, and were easily iden¬ 
tified by the characteristic arsenical 
poisoning displayed by them when suc- 
In these tests the specimens were con¬ 
fined in wire cages and the dust was 
applied with a small hand duster. 
The dusts were prepared by impreg¬ 
nating hydrated lime with a 40 per cent 
nicotine sulphate solution according to 
formula No. 2, on page 5 of Farmers’ 
Bulletin 1282. 
