202 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 13 
capacity. Many of the above phases of the problem are closely related,, 
consequently it is by no means a simple one. 
Method of Application 
The granulated or liquid sodium cyanide was placed in a shallow 
trench (2 to 4 inches deep) about the base of the peach tree. After the 
poison was applied the soil was piled up about the tree to a height of 
6 to 10 inches and then tramped down with a hoe. In the liquid treat¬ 
ments (sodium cyanide dissolved in water) the solution was permitted 
to partially soak into the ground before the dirt was piled about the 
tree. When the dry granular sodium cyanide was used it was evenly 
distributed in the trench and not permitted to come directly in con¬ 
tact with the tree. 
Response of the Larvae to Sodium Cyanide 
What is the minimum dosage which will kill a sufficient number of 
larvae to be a practical control (Tables I to II)? In this preliminary 
report three typical experiments will be discussed. These are taken 
from a number of experiments conducted under varying conditions in 
eight orchards throughout New Jersey. Table I shows the results ob¬ 
tained at Clementon, N. J., early in November, 1918, where experi¬ 
ments were conducted under two soil conditions, a light sandy soil 
and a gravel loam soil. In these experiments the percentage of kill is 
based on an actual count of the dead and living larvae found in the 
treated trees. The percentage of dead larvae is probably greater than 
indicated, because in “worming’’ the trees one cannot be sure that all 
of the dead larvae have been found. A dead larva gives no indication 
of its presence in a tree while a living larvae does. To remove all of 
the dead borers would require severe cutting of the trees. 
Table II shows the results obtained at Clementon, N. J., in May, 
1919. The percentage of reduction in the infestation is very similar 
to that obtained early in November, 1918. In this table the per- 
Table I. The Effect of Sodium Cyanide on Peach-Tree Borers (per Tree) Present in Nine- 
Year-Old-Trees (Five Trees in Each Plot) in November, 1918, at Clementon, N. J. 
Series 
Treatment 
Living larvae 
per tree 
Dead larvae 
per tree 
Total larvae 
per tree 
Percentage 
killed 
1 
§ oz. to 1 gal. 
1.6 
3.4 
5.0 
68% 
2 
1 oz. to 1 gal. 
.4 
5.6 
6.0 
93% 
3 
Check 
10.6 
0 
10.6 
\ 
4 
1 oz. to 1 gal. 
1.2 
3.6 
4.8 
75% 
5 
Is oz. to 1 gal. 
.4 
6.4 
6.8 
94% 
6 
1 oz. dry 
.8 
2.8 
3.6 
77% 
7 
Check 
5.0 
0 
5.0 
Series 1-3 in sandy soil. 
Series 4-7 in gravel loam soil. 
