n88 
Journal of Agricultural Research 
Vol. V t No. a 5 
difference in the total effective temperatures is reduced to a minimum. 
At the start some arbitrary zero must be chosen and the effective tem¬ 
peratures computed above this. Then it is necessary to remove degree 
by degree at the top or bottom and note each time whether the differ¬ 
ence in the total effective temperatures becomes larger or smaller. This 
process may be charted so that the general tendency can be seen. The 
figures found in the writer's attempt to establish the zone of effective 
temperatures for the boll weevil at 56 per cent humidity will illustrate 
the manner in which the points desired were ascertained. These results 
are presented in figure 2, and it will be seen that the first tentative zone 
chosen was 51 0 to ioo° F. By much testing it was narrowed to within 
the limits of 75 0 to 92 0 F., for which the optimum is practically 83.5°. 
Having obtained the limits of the zone, the records of development 
in cotton squares at a mean humidity of 55.9 per cent to 56.9 per cent, 
made at Victoria, Tex., in 1913, by Mr. B. R. Coad, of the Bureau of 
Entomology, are as shown in Tables I and II. 
Table I. —Records of development of Anthonomus grandis at Victoria, Tex., in ipij, 
at a humidity of 55.Q to $6.g per cent 
Experiment. 
Mean hu¬ 
midity. 
Date of 
ovipo- 
sition. 
Time of 
maturing. 
Actual 
period of 
develop¬ 
ment. 
Number of 
weevils ob¬ 
served. 
Total 
weevil 
days. 
Actual temperature. 
Male. 
Female. 
Abso¬ 
lute 
maxi¬ 
mum. 
Abso¬ 
lute 
mini¬ 
mum. 
Mean. 
1 . 
2 . 
3 . 
4 . 
5 . 
Mean.... 
Per cent. 
56.1 
56.4 
56.6 
56.9 
55-9 
56.2 
July 27 
July 26 
July 27 
July 27 
May 22 
Aug. 9 
Aug. 8 
Aug. 10 
Aug. 11 
June 7 
Days. 
13 
13 
14 
is 
16 
6 
1 
1 
Total. 8 
2 
3 
1 
1 
7 
104 
52 
14 
15 
16 
201 
0 F. 
X04 
104 
104 
X04 
9 5-5 
0 F. 
73-2 
73-2 
73-2 
73-2 
54 * S 
op 
88.2 
88.3 
88.3 
88.3 
78. 3 
Table II.— Records of development of Anthonomus grandis at Victoria, Tex., in IQ13 , 
in the zone of effective temperatures , 75 0 to Q2° F. 
1 <* 
Experi¬ 
ment. 
2a 
Num¬ 
ber of 
weevils. 
So 
Mean 
humid¬ 
ity. 
4o 
Humid 
time 
units. 
50 
Period 
experi¬ 
encing 
effective 
temper¬ 
ature. 
60 
Total 
effective 
weevil 
days. 
7 o 
Mean 
effective 
temper¬ 
ature. 
80 
Effective 
thermal 
units. 
9 o 
Mean 
daily 
effective 
temper¬ 
ature. 
units. 
lOo 
Total 
effective 
temper¬ 
ature. 
llo 
Humid¬ 
ity plus 
effective 
temper¬ 
ature. 
Per ct. 
Days. 
0 F. 
°F. 
°F. 
1. 
8 
56.1 
448.8 
8.19 
65-52 
83.8 
670.4 
8.8 
72.0 
139-9 
3. 
4 
56.4 
225.6 
8.18 
32.72 
83.8 
335-2 
8.8 
71.98 
140. 3 
3 --. 
1 
56.6 
56.6 
8.86 
8.86 
83.6 
83.6 
8.6 
76.1 
140. 3 
4 . 
1 
56-9 
$ 6-9 
9-52 
9*52 
83- 7 
83-7 
8.7 
82.82 
140.6 
s. 
1 
55-9 
55-9 
9 - 95 
9 - 95 
82.6 
82.6 
7-6 
75-6 
138.5 
Total.... 
IS 
843.8 
126. 57 
if 255 -5 
Average. 
56. 2 
8-43 
83.7 
8. *7 
73*3 
T1Q. Q 
Differ¬ 
f 
A jy* y 
ence... 
I, 2 
xo.84 
2* 1 
a Column 4 is product of columns 2 and 3. Column 5 is computed from the actual records. Column 6 is 
the product of 2 and 5. Column 8 is the product of 2 and 7. Column 9 is 7 minus the zero (75 0 F.). Column 
10 is the product of columns 5 and 9. Column 11 is the sum of columns 3 and 7. 
