6 i6 
Journal of Agricultural Research 
Vol XXVI, No. ia 
vidual seems to extend beyond the ability of a large percentage of them to 
hatch and to lend vigor to the growing progeny, pr omoting a higher per¬ 
centage of emergence. To avoid complicating figure i, this varying 
difference between percentage of hatching and percentage of emergence 
is not illustrated, the former being omitted. 
TabmJ IV. Minimum^ maximum, and average length of the developmental periods of 
adults resulting from eggs laid by one female (No. 48) 
Length of developmental period. 
Date of ovipo- 
sition. 
F*f* 
laid. 
Bees 
hatched . 
emerged. 
Total. 
Males. 
Females. 
<? 
9 
To¬ 
tal. 
Mini¬ 
mum. 
Maxi¬ 
mum. 
Aver¬ 
age. 
Mini¬ 
mum. 
Maxi¬ 
mum. 
Aver¬ 
age. 
Mini¬ 
mum. 
Maxi¬ 
mum. 
Aver¬ 
age. 
Days. 
Days. 
Days. 
Days. 
Days. 
Days . 
Days. 
Days. 
Days. 
Sept, as. 
20 
14 
5 
9 
14 
xi 6 
155 
130 
116 
132 
X22 
xi 6 
i55 
134 
a 6 ........ 
14 
12 
3 
3 
6 
X2X 
163 
143 
X2I 
158 
140 
123 
163 
145 
27. 
*7 
13 
2 
4 
6 
117 
174 
149 
117 
158 
138 
133 
i74 
I 5 S 
28. 
7 
s 
3 
2 
S 
X28 
152 
138 
128 
152 
139 
128 
146 
137 
29. 
6 
5 
z 
2 
3 
X22 
135 
127 
135 
i35 
135 
122 
123 
123 
_ 30 « . 
5 
5 
X 
0 
X 
x 6 x 
x 6 i 
x 6 x 
l 6 l 
161 
l6l 
0 
0 
0 
Oct. 1 . 
7 
2 
0 
X 
X 
158 
158 
158 
O 
0 
O 
15 8 
158 
158 
2 . 
3 
2 
0 
0 
0 
3 . 
3 
r 
0 
0 
0 
4 . 
2 
1 
0 
0 
0 
6 ........ 
2 
0 
0 
0 
0 
Total or 
average 
86 
60 
IS 
21 
36 
Il6 
174 
138 
Il6 
161 
135 
116 
174 
140 
0 One male was dissected alive from the cowpeas after 21S days of development. 
A study of all the data, which are here published only in abstract, 
suggests that the age of females affects the rapidity of the development of 
their progeny. For example, the average developmental periods of all 
the weevils which resulted from eggs laid October 7 are roughly propor¬ 
tional to the age of the parent females on that date. Females Nos. 51, 
52, 57, 60, and 61 were respectively 12, 12, 10, 6, and 5 days old on 
October 7; and the average developmental periods of all the progeny 
from the eggs laid that day by these weevils were 206, 206, 172, 167, and 
165 days. This effect is supported by other evidence in the complete 
analyses, which, however, are too extensive to be published. 
It is of course generally recognized that the moisture content of beans 
and other seeds influences the development of insects feeding in them. 
The moisture content of the cowpeas used in these experiments was not 
determined, but they were kept under uniform conditions which would 
tend to cause the percentage of moisture to change equally in all the seeds. 
Possibly dryness was responsible for some larval mortality, but figure 1 
shows that the principal factor influencing mortality of immature forms 
is the age of the mother at the time of oviposition. 
CONCLUSIONS 
The results of this study indicate that the average lengths of the devel¬ 
opmental periods of larvae of Bruchus quadrimaculatus which hatch from 
eggs laid on successive days in the fall tend to be inversely proportional 
to the duration of the exposure of the embryos and young larvae to warm 
weather. 
The age of a female weevil at the time of laying a given day’s batch 
of eggs influences (1) the number of eggs in the batch, and (2) the vitality 
of the eggs, as indicated by (a) the percentage of hatching, (b) the ability 
of the resultant larvae to become adults, and ( c ) the average duration of 
the developmental periods of the progeny. 
o 
