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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 13 
The one ounce treatments reduced the living larvae 85 to 91 per cent 
in the soil level and below ground zones while above ground the sodium 
cyanide was not very effective. The dry sodium cyanide did not 
materially effect the larvae above ground while the liquid sodium 
cyanide apparently did (55 per cent). This difference may be due to 
the fact that in applying the liquid sodium cyanide the poison was 
poured against the tree above ground. It is probable that a greater 
percentage of kill above ground would have resulted with the dry 
sodium cyanide if it had been sprinkled about the tree at soil level and 
not placed in a trough 2 to 4 inches deep. 
The size of the larvae is not recorded in the tables, but our records 
show that small larvae are killed more readily than larger ones. This 
may be due to the fact that the small larvae are usually located near 
the outer surface of the trunk while the large ones may be deeply 
embedded in the tree. In early autumn the majority of the larvae 
are small and located near the outside of the tree. This points to the 
conclusion that the best time of the year to kill the borers is during 
September or early in October. 
Response of the Peach Trees to Sodium Cyanide 
a 
What is the maximum dosage peach trees of varying ages will stand? 
In Tables IV and V a few of the typical and unusual results are recorded 
from various orchards. Table IV shows the results obtained with 
eight- and nine-year-old trees. Two and three ounce treatments 
killed or injured many of the trees when applications were made in 
May and June. Similar applications made in October gave the same 
results. When one and one half ounces and one ounce treatments to a 
gallon of water were applied in November, 1918, to eight-year-old 
trees in a gravel loam soil all of the trees died which received one and 
one half ounces and 20 per cent died which received one ounce. A one 
ounce dry sodium cyanide treatment was made at the same time and 
no tree was seriously injured. In the same orchard a number of 
Table IV. The Effect of Sodium Cyanide on Peach Trees Eight and Nine Years of Age, 
1918-19 
Treatment 
. Date 
Soil 
Normal trees 
Injured trees 
Dead trees 
\ oz. to 1 gal. 
Oct. 29, ’18 
Sandy 
5 
0 
0 
1 oz. to 1 gal. 
Oct. 29, ’18 
Sandy 
5 
0 
0 
1 oz. to 1 gal. 
Nov. 10, ’18 
Gravel loam 
4 
0 
1 
oz. to 1 gal. 
Nov. 10, ’18 
Gravel loam 
0 
0 
5 
1 oz. dry 
Nov. 10, T8 
Gravel loam 
5 
0 
0 
1 oz. to 1 gal. 
May 15, T9 
Gravel loam 
3 
0 
0 
1§ oz. to 1 gal. 
May 15, T9 
Gravel loam 
3 
0 
0 
1 oz. dry 
May 15, T9 
Gravel loam 
3 
0 
0 
1£ oz. dry 
May 15, T9 
Gravel loam 
3 
0 
0 
2 oz. dry 
May 15, T9 
Sandy 
1 
2 
0 
3 oz. dry 
May 15, T9 
Sandy 
3 
0 
0 
3 oz. dry 
June 7, T9 
Sand loam 
0 
0 
5 
