MISCELLANEOUS INSECTICIDE INVESTIGATIONS. 7 
Experiment III. 
COMPARISON OP THE KILLING EFFECT OF VARIOUS ARSENICALS ON LARVAE OF THE FALL 
WEB WORM. 
In this experiment the same arsenicals were used as in Experiment 
I, all the other materials being omitted. However, since half-grown 
larvae were used the strength of the materials was doubled. The 
results are shown in Table III. 
Table III. — Tests of the hilling effect of various arsenicals on the fall webuorm. Larvx 
half grown. 
{Experiment started July 24, 1912, Benton narbor, Mich.; 20 larvae in each lot.] 
Name and dilution. 
Arsenate of lead, di. , 2-55 
Arsenate of lead, tri., 2-42 
Arsenate of lead, di. and hi., 2-50 
Arsenate oflead, triplumbic, com. (1), 
4-50 
Arsenate of lead, com. (2), 4-50 
Arsenateoflead.com. (3), 4-50 
Arsenate of calcium, c. p. (powder), 2-50. 
Arsenate of iron, c. p. (powder), 4-50. . . 
Arsenate of iron, h. in. , 3 T V50 
Arsenate of zinc, c. p. (powder), 2-46... 
Arsenate of zinc, h. m., l T 6 -50 
Arsenic sulphid , 2-54 
Arsenic tersulphid, 1-50 
Arsenic trioxid, 1-56 
Arseniteoflime,4 pis. -50 
Arsenate of zinc, c. p. (l), 2—43 
Arsenite of zinc, com. (2), 3-50 
Arseniteof zinc, com. (3), 14-50 
Arsenite of zinc, com. (4), 1J-50 
Check ( unsprayed ) ( 1 ) 
Check (unsprayed) (2) 
Dates of examination and number of 
larv r ac dying in each lot. 
July. 
27 28 
August. 
Total 
num- 
ber 
dead. 
Num- 
ber 
days re- 
quired 
to kill. 
20 
20 
20 
20 
20 
20 
20 
12 
9 
20 
20 
20 
20 
U9 
20 
U8 
20 
20 
U9 


Square 
inches 
foliage 
con- 
sumed. 
1.22 
.60 
.43 
.84 
.94 
.37 
1.15 
( 2 ) 
( 2 ) 
2.03 
.87 
.95 
.19 
.06 
.56 
.15 
1.08 
.94 
.41 
( 2 ) 
( 2 ) 
Remainder escaped. 
2 Not measured. 
The results of these tests agree very well with the results obtained 
from Experiment I. The experiment was discontinued August 12, 
when all the larvae were dead except in the case of arsenate of iron, 
chemically pure, where 8 larva? still remained living, and arsenate 
of iron, homemade, where 11 remained living. All the larvae on the 
unsprayed lots were alive at the time the experiment was closed. 
Experiment IV. 
FIELD TESTS OF VARIOUS ARSENICALS AGAINST THE CODLING MOTH IN MICHIGAN, 1912. 
Several arsenicals were tested in comparison with arsenate of lead 
against the codling moth in Mr. J. T. Beckwith's apple orchard in the 
vicinity of Benton Harbor. The trees were of the Ben Davis variety 
and about 35 years of age. The plats consisted of from 4 to 12 trees, 
and the fruit was counted from 3 trees of each plat. The extent of 
foliage hi j ury from the various sprays was also noted. The homemade 
