February, ’18] HOWARD: INSECTICIDES and diabrotica 
77 
Table I—5 Experiments with 9 Insecticides—11 Tests 
100 Beetles per Test. Check of 100 beetles per experiment. Beetles on plants 24 hours unless noted. Live beetles 
counted at beginning and end of experiment 
Date 
1916 
Insecticide 
Rate per 
50 Gal. 
5 Days 
on Planl 
Alive 
ifter Put 
,s, Total 
Dead 
Total Killed by 
Insecticide 
(% Efficiency) 
July 28 
Lead arsenate paste 
4 
37 
45 
41 
Check 
91 
4 
Aug. 2 
B or deaux-lead-arsenate 
/ 2-4 
93 
1 
0 
Check 
\4~ 
91 
1 
Aug. 3 
Calcium arsenate powder 
2 
59 
13 
1 
Check 
84 
12 
Aug. 11 
Check 
/ 2-4 
97 
0 
B ordeaux-lead-arsenate 
\ 4- 
87 
2 
2 
Lead arsenate paste 
4 
90 
6 
6 
Sweet lead arsenate 
4 
85 
13 
13 
Paris green 
1 
77 
20 
20 
Aug 14 
Check 
*92 
5 
t 
Cobalt arsenate paste 
2 
92 
8 
3 
Zinc arsenate powder 
2 
80 
19 
14 
Zinc arsenite powder 
2 
65 
26 
21 
Arsenic bi-sulphide 
2 
94 
3 
-0 
* After four days, 
t On plants 48 hours. 
Note: Beetles killed by parasites counted as living. Beetles which escaped in handling also counted as living. 
was covered on three sides and top with 20 mesh pearl wire. The 
fourth side was covered with heavy muslin, in which were sewed 
three sleeves placed in the proper positions to enable one to insert 
his head and arms and work with ease. The bottom was covered 
with heavy muslin which had been sewed about the plant. 
The insecticides were used in different proportions, however, the 
aim being to have approximately equal amounts of arsenic pentoxide 
per unit of spray. Lead arsenate was used in the same proportion 
as in 1916, but Paris green and zinc arsenite were varied to suit, so 
that the former was used at the rate of 1 to 60, the latter at 1 to 40. 
Fish oil soap was used in each test of July 6 except in the case of the 
sweetened lead arsenate, at the rate of 2 pounds to 50 gallons. Chemi¬ 
cal analyses of the insecticides showed them to be representative of 
the preparations on the market. 
The poisoned bran mash used was made according to Farmer’s 
Bulletin No. 747, but pulp of muskmelon was substituted for other 
fruit. The results of these experiments are given in Table II. 
The general average of all tests gives, I believe, a very good idea 
of the relative value of these insecticides in the field, and what one 
might expect when the repellent properties of Bordeaux mixture are 
considered. It is true that all these insecticides are more or less 
repellent. This has been determined in a different series of experi¬ 
ments which are not recorded here. The general average may be 
