90 
THE SPRING GRAIN-APHIS OB ' l GREEN BUG. ' ' 
Tabulated, the results of Mr. Vickery's rearings are as follows: 
Table IX. — Experiments with 5 viviparous females of Toxoptera graminum to determine 
minimum temperature at which reproduction will take place. Richmond, Ind., 
December, 1908. 
Date. 
Temperature. 
Number 
of young 
produced. 
Minimum. 
Maximum. 
Dec. 3 
4 
5 
6 
7 
8 
9 
°F. 
40 
40 
40 
40 
26 
35 
39 
°F. 
45 
41 
53 
45 
49 
50 
50 

1 
6 

1 
7 

After December 9 the outside temperature increased so that con- 
trol indoors was not possible. 
At Dallas, Tex., January 3 to 14, out of doors and under natural 
conditions, with thermometer within a few feet of the five female 
Toxoptera 1 to 3 days after maturity, Mr. Urbahns found that 
young were produced as follows: 
Table X. — Experiments with 5 viviparous females of Toxoptera graminum to determine 
minimum, temperature at ivhich reproduction will take place. Dallas, Tex., January, 
1908. 
Temperature. 
Date. 
Number of young produced by 
each individual. 
Minimum. 
Maximum. 
°F. 
°F. 
Total. 
Jan. 3 
47 
68 
1 
1 
1 
1 
1 
5 
4 
55 
78 
3 
3 
1 
5 
4 
16 
5 
37 
69 
3 
3 
1 
2 
2 
11 
6 
22 
42 






7 
21 
32 






8 
29 
45 





9 
44 
74 
4 
2 

3 
4 
13 
10 
37 
74 
4 
4 
0) 
3 
5 
16 
11 
14 
15 





12 
10 
22 





13 
21 
32 





14 
Total.. 
32 
71 





15 
13 
3 
14 
16 - 
1 -1 
Died. 
