298 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 11 
will be loose enough to allow the gas to diffuse between them. Thus 
the leakage surface is greater, and, moreover, the actual cubical con¬ 
tents is increased beyond that based on the measurement of a tight 
tape drawn around the tented tree. 
The following “tent data” are presented to show the calculations 
for trees of widely different shapes. Examination of the table will 
show such variations as have already been alluded to in the case of the 
two trees mentioned, as well as further data regarding the surface of 
the geometrical figure, the ground surface, the relation of tent surface 
to volume, and the relation of dosage to tent surface and volume. 
Tent Data 
Size 
tree 
Dose® 
100% 
Tent 1 
surface 
Tent* 
volume 
Rel. of dose® to surface and 
volume 
Surface Volume 
Ground 
surface 
Surface of® 
hemisphere 
and cylin¬ 
der 
Ratio of 
tent 
surface to 
volume 
a 
10 x 16 
3 oz. 
79 sq. ft. 
55cu.ft. 
1 oz. to 26 sq. ft. to 18 cu. ft. 
20 sq. ft. 
64 sq. ft. 
1 to .701 
b 
14x20 
3 
154 
131 
1 
51 
43 
31 
103 
1 
.851 
c 
16x28 
4 
201 
248 
1 
50 
62 
62 
153 
1 
1.232 
d 
18x36 
5 
254 
394 
1 
51 
79 
103 
206 
1 
1.542* 
e 
20x24 
4 
314 
300 
1 
78 
75 
45 
187 
1 
.954 
f 
20x40 
6 
314 
540 
1 
52 
90 
127 
254 
1 
1.167 
8 
30x30 
7 
707 
765 
1 
101 
109 
71 
368 
1 
.541 
h 
30x40 
9 
707 
1,176 
1 
78 
131 
127 
454 
1 
1.665 
i 
30x60 
13 
707 
1,850 
1 
54 
142 
286 
572 
1 
2.618' 
j 
34x50 
13 
908 
1,950 
1 
69 
150 
198 
622 
1 
2.147 
k 
38x40 
11 
1,134 
1,686 
1 
103 
153 
127 
614 
1 
1.486 
1 
38x64 
18 
1,134 
3,188 
1 
63 
177 
325 
834 
1 
2.811 
m 
40x50 
15 
1,257 
2,546 
1 
83 
170 
198 
773 
1 
2.026 
n 
40 x 60 
18 
1,257 
3,396 
1 
70 
189 
286 
873 
1 
2.704 
0 
42x44 
14 
1,385 
2,259 
1 
99 
161 
154 
748 
1 
1.631 
P 
44x68 
22 
1,520 
4,492 
1 
69 
204 
367 
1,076 
1 
2.954 
<1 
45x60 
20 
1,590 
3,971 
1 
79 
198 
286 
1,022 
1 
2.497 
r 
49x54 
25 
1,886 
3,878 
1 
75 
155 
232 
1,058 
1 
2.056 
8 
49x68 
25 
1,886 
5,413 
1 
75 
216 
367 
1,245 
1 
2.870 
t 
50x60 
23 
1,963 
4,687 
1 
85 
203 
286 
1,172 
1 
2.336 
U 
50x76 
76 
1,963 
6,461 
1 
67 
223 
459 
1,375 
1 
3.290 1 
o o 
II II 
= Distance over. 
‘Circumference. 
1 0*x .7854. 
, C* / ° V 
.£+£2. 
2» 2 
C* 
—• 1 111 • 
4 
*C*x. 07958. 
* On basis of 100% schedule now 
in general use. 
Summary 
The greatest concentration of hydrocyanic acid gas occurs in the 
upper half of tented trees. 
The difference in the effect on insects at the top and bottom of a tree 
may be great enough to seriously impair the results. Little difference 
in gas concentration has been indicated by our experiments between 
the top and center of the tree. 
Better killing of insects was secured in the low tent (22 ft. x 44 ft.) 
than in the high tent (31 ft. x 31 ft.). The actual difference was 19.4 
per cent. These tents represent the most extreme shapes in citrus trees. 
