14 
Table 4. — Duration of the larval stage of Hyp era brunneipennis on 
alfalfa, hubam, and sourclover, Yuma, Ariz., 1940 
L ength of larval stage (days) 
Date 
started 
Mean days 
in stages 
Range 
Food 
1st 
2nd 
3rd 
4th 
Mean 
Alfalfa 
1/29 
6.6 
8.0 
9.8 
6.6 
30-32 
31.0 
Hubam 
1/30 
7.0 
10.1 
8.1 
7.2 
30-40 
32.4 
Sourclover 
1/30 
9.3 
8.2 
7.6 
7.6 
29-36 
32.7 
Alfalfa 
2/12 
9.4 
4.1 
3.8 
6.2 
23-27 
23.5 
Hubam 
2/12 
10.0 
5.6 
5.8 
7.0 
27-32 
28.4 
Sourclover 
2/12 
9.7 
5.2 
5.1 
6.9 
23-24 
26.9 
Alfalfa 
2/24 
3.6 
4.3 
4.3 
7.8 
20-22 
20.0 
Hubam 1/ 
— 





— 
Sourclover 
2/25 
5.6 
5.0 
6.8 
7.7 
21-29 
25.1 
Alfalfa 
3/2 
4.0 
3.8 
6.4 
5.9 
19-21 
20.1 
Hubam 
3/2 
5.9 
5.5 
5.7 
5.0 
21-27 
22.1 
Sourclover 
3/2 
5.3 
7.4 
2/ 

~ 
Alfalfa 
3/10 
6.8 
4.4 
4.4 
5.3 
19-25 
20.9 
Hubam 
3/10 
7.0 
4.2 
4.6 
6.1 
21-23 
21.9 
Sourclover 
3/10 
7.8 
4.9 
4.2 
2/ 

— 
Alfalfa 
3/21 
3.2 
3.5 
4.3 
6.3 
17-21 
17.3 
Hubam 
3/21 
5.7 
5.2 
5.4 
5.1 
19-23 
21.4 
Sourclover 
3/21 
4.9 
4.2 
4.2 
6.4 
17-23 
19.7 
1/ No cage established. 
2/ Cage closed because of complete mortality, 
was somewhat obscured by greater abundance of larvae resulting frcm a larger 
parent adult population. Ecological studies begun in sourclover on March 13 
revealed a sizeable larval population and an abundance of eggs, indicating 
a continued increase of larvae. However, the larval population failed to 
increase and soon began to decline, with relatively few developing to ma- 
turity. Comparison cf data on the two hosts indicated that sourclover was a 
more suitable host than alfalfa, but even on sourclover only a minor portion 
of the population developed to the adult stage. Consequently this plant must 
be considered only as the most satisfactory of the available hcsts. Com- 
parative data on the abundance and development of larvae on alfalfa and sour- 
clover are presented in table 5. 
