78 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 11 
Table II—2 Experiments with 12 Insecticides—12 Tests 
100 beetles per test. Check of 100 beetles per experiment. Beetles on sprayed plants 24 hours. Living beetles 
counted at beginning and end of each experiment, dead beetles counted every day. Summary given in table 
Date 
1917 
Insecticide 
Formula 
5 Days 
on Plants 
Alive 
fter Put 
i, Totals 
Dead 
Total Killed by 
Insecticide 
(% Efficiency) 
July 6 
Lead arsenate, wet 
2 lbs. Pwdr. 
77 
24 
10 
50 Gal. 
Lead arsenate and molasses 
50 Gal. 
9 qt. Mol. 
63 
38 
24 
Lead arsenate and Bordeaux 
2-50 
2-4-50 
48 
48 
34 
Zinc arsenite, wet 
1 lb. Pwdr. 
40 Gal. 
48 
49 
35 
Bran mash 
24 
74 
60 
Paris green 
1 lb. to 
60 Gal. 
49 
43 
29 
Check 
87 
14 
Aug. 10 
Lead arsenate, wet 
Same as 
85 
15 
10 
Lead arsenate and molasses 
above 
81 
18 
13 
Lead arsenate and Bordeaux 
Same as 
above 
84 
10 
5 
Zinc arsenite, wet 
Same as 
above 
80 
20 
15 
Lead arsenate, dust 
1-3 
Lime 
85 
14 
9 
Paris green, wet 
1-60 
87 
5 
0 
Check 
95 
5 
misleading in one respect, for sweetened lead arsenate is more effective 
than indicated. However, in the field, where most of the above in¬ 
secticides were given a thorough trial on a good acreage in 1917, the 
results were not noticeably different than with any of the others, 
although sweets have been shown to be attractive in other experiments. 
The poisoned bran mash is not included in this summary, since subse¬ 
quent tests showed that even sprayed plants were more attractive. 
The average of the two seasons’ results is as follows: 
Zinc arsenite, average of 3 tests. 24% efficient 
Lead arsenate, average of 4 tests. 17% efficient 
Sweetened lead arsenate, 3 tests. 17% efficient 
Paris green, average of 3 tests. 16% efficient 
Zinc arsenate, 1 test. 14% efficient 
Bordeaux lead arsenate, 4 tests. 14% efficient 
Lead arsenate dust, 1-3, 1 test. 9% efficient 
Cobalt arsenate, 1 test.. 4% efficient 
Calcium arsenate, 1 test. 1 % efficient 
Arsenic bi-sulphide (Realgar), 1 test. 0% efficient 
Zinc arsenate is too unstable, in its present commercial form, at 
least, to be of importance. Cobalt arsenate needs no further comment. 
Arsenic bi-sulphide is too heavy to stay in suspension and does not 
spread well. This fact no doubt accounts for its poor showing. 
Zinc arsenite is apparently more effective than arsenate of lead. 
The fact that a higher per cent efficiency was indicated by collec- 
