220 
Journal of Agricultural Research 
Vol. I, No. 3 
Table? I. Incubation periods of eggs of Calliephialtes sp . and the relation between incu¬ 
bation period and temperature at Vienna , Va., IQI2 . 
Incubation period. 
Number of eggs hatching in— 
Total. 
Average 
mean tem¬ 
perature. 
Apr. 
May. 
June. 
July. 
Aug. 
Sept. 
Oct. 
1 day. 
1.5 days. 
2 days. 
2 .5 days. 
3 days. 
3.5 days. 
16 
68 
169 
r 5 
40 
2 
11 
2 
4 
4 
36 
20 
7 
1 
49 
75 
35 
7 
5 
*7 
57 
19 
1 
1 
1 
4 
6 
13 
2 
5 
5 
10 
6 
29 
26 
9 
7 
9 
7 
4 
2 
87 
250 
255 
7 2 
75 
16 
24 
12 
20 
4 
8 
°F. 
78. 0 
74.4 
70. 2 
67. 0 
62. 7 
58. 7 
58.9 
55-3 
55-6 
57-2 
54 - 8 
53 - 2 
4 days. 
4.5 days. 
1 
1 
1 
5 d ays. . 
5.5 days. 
8 
6 days. 
3 
3 
6.5 days. 
7 days . 
2 
2 
Total. 
Average. 
14 
5- 43 
330 
2. 15. 
68 
1.74 
171 
54 
97 
1. 60 
36 
2. 64 
109 
3. 18 
825 
2. 14 
69. 96 
The relation of incubation period to the average mean temperature 
based on the figures of Table I is shown in graphic form in figure 7. Ref¬ 
erence to this dia¬ 
gram will show that 
with a fair degree of 
constancy the dura¬ 
tion of the incuba¬ 
tion period varied 
inversely as the aver¬ 
age mean tempera¬ 
ture. The tempera¬ 
tures that are far¬ 
thest from the curve 
(those of 3.5, 4.5, 
and 5.5 days) are 
based on the incuba¬ 
tion periods of few 
eggs (16, 12, and 4, 
respectively), and 
the possibility of 
error was therefore 
greater than had the 
number been larger. 
Eig. 7*—Diagram showing relation between incubation period of eggs of 
Calliephialtes sp. and average mean temperature at Vienna, Va., 1912. 
THE TARVA 
larva (fig. 8) is 
across the head. 
The newly hatched 
yellowish, slightly shorter than the egg, and widest 
The head is distinctly separated from the rest of the 
