10 
Table II. — Relative effectiveness of a single fall application of stated doses of 
p-dichlorobenzene, 1916-1918. 
Observation. 
Application per tree. 
Check un- 
1 ounce. 
\ ounce. 
\ ounce. 
1 ounce. 
treated. 
Total number of trees. 
10 
4 
6 
25 
11 
4.1 
2.5 
70 
88 
61 
27 
90 
9 
3.3 
1 
88 
272 
226 
46 
98 
6 
2.1 
.36 
95 
298 
256 
42 
85 
6 
2 
.28 
96 
224 
22 
202 
1,669 
44 
Average number of larvae per tree for trees infested . . 
Average number of larvae per tree for total number 
8.2 
7.4 
Approximate percentage of control 

The time of application varied from the last of August to the last 
of September, yet in no case was there a very decided departure from 
the general average of control given in the table. In some cases when 
application was made about the 25th of August the fumigation was 
apparently over a little too soon, indicated by a slight infestation of 
newly hatched larvae. On the other hand, applications made the last 
of September, while entirely effective, had the disadvantage of in- 
complete evaporation. The ideal time apparently was 'in early Sep- 
tember, approximately the 10th. 
In 1917 about 80 trees were treated at Springfield with a 1-ounee 
dose each. One plat received one application on July 7; one plat 
two applications, the first on July 7 and the second on August 24 ; and 
one plat one application on August 25. The plat receiving one appli- 
cation July 7 gave a control of 45 per cent when examined on October 
11. The plat receiving two applications gave a control of 96 per cent, 
and the plat receiving one application on August 25, 90 per cent. 
Table III gives the results of this treatment. 
Table III. — Relative effectiveness of one and two applications per season of a 
1-ounce dose of p-dichlorobenzene per tree, Springfield, W. Va., 1917. 
Applications. 
Dates of 
exami- 
nation. 
xr„™i^,. ~e i-r^c Number of active 
>. umber of trees— larvae 
Percent- 
age of 
control 
Number. 
Date. 
Treated. 
Ex- 
amined. 
Total. 
Average 
per tree. 
1 
July 7 
/...do... 
\Aug- 24 
Aug. 25 
Oct. 11 
}...do... 
Oct. 16 
29 
38 
13 
20 
20 
13 
28 
66 
5 
8 
169 
3.3 
.25 
.6 
6 
45 
2 
96 
1 
90 
Check 

The difference in control between the plat treated twice and that 
treated once on August 25 is too slight to be of special importance, 
and certainly not sufficient to warrant the double application in prac- 
tice. Aside from consideration of economy two applications per 
