614 
Journal of Agricultural Research 
Vol. XXVI, No. 12 
Emergence of the progeny began December 18, 1919, and ended May 
17, 1920, a period of 152 days, over five times the duration (28 days) 
of the period over which the eggs were laid. The number of days re¬ 
quired by each emerging weevil to develop from egg to adult was indi¬ 
vidually recorded, and data in Table II show the number of adults which 
emerged from the eggs laid by each female, as well as the average develop¬ 
mental period of all her adult progeny. The average time required for 
the development of all the males (not separately shown in the table) was 
a fraction of a day less than that required by the females. The shortest 
developmental period of the entire brood was 91 days. On the other 
hand, during the summer this minimum period has been observed by 
the writers to be about one month. 
Following the supposed completion of the emergence of this series, 
the cowpeas were dissected and 70 live weevils in various stages of 
development were found. These had been developing for an average of 
204 days. A live larva was dissected from the cowpeas as long as 
2 35 days after the eggs were laid, and it is very probable that uninter¬ 
rupted development on the part of the 70 forms dissected from the seeds 
would have resulted in developmental periods in excess of 8 months; 
The following tabulation (Table III) deals with the emergence of the 
progeny, arranged to show the results from the daily oviposition. 
Table III .—Summary of the emergence resulting from eggs laid each day by 61 Bruchus 
quadrimaculatus 
Date laid. 
Daily total 
of eggs. 
Hatched. 
Eggs pro¬ 
ducing 
adults. 
Development period. 
Mini¬ 
mum. 
Maxi¬ 
mum. 
Average. 
^ 0 I919 ' 
Per ceni. 
Per cent. 
Days. 
Days. 
Days. 
Sept. 18. 
52 
8l 
65 
91 
171 
IO4 
19. 
89 
75 
55 
93 
174 
108 
20. 
167 
84 
7i 
9i 
137 
IOQ 
21. 
212 
77 
68 
95 
181 
114 
22. 
30 
77 
70 
93 
205 
no 
23. 
463 
77 
67 
98 
184 
120 
24. 
660 
74 
63 
97 
203 
I2J 
25. 
634 
70 
59 
no 
188 
128 
26. 
623 
70 
58 
105 
217 
I30 
27. 
478 
66 
53 
no 
217 
133 
28. 
304 
54 
40 
“5 
212 
134 
29. 
184 
56 
44 
“5 
I98 
139 
30. 
129 
50 
36 
103 
195 
148 
Oct. 1. 
129 
43 
28 
131 
175 
ISO 
2. 
64 
44 
19 
138 
l8l 
156 
3. 
88 
47 
26 
X 3 X 
203 
159 
4. 
67 
3i 
18 
132 
212 
156 
5. 
47 
55 
34 
119 
174 
146 
6. 
5i 
53 
33 
136 
T 99 
154 
7. 
43 
63 
26 
156 
206 
175 
8 . 
39 
59 
28 
132 
203 
162 
9- •. 
30 
50 
37 
155 
221 
175 
10. 
18 
67 
33 
151 
186 
167 
11. 
9 
33 
33 
163 
167 
165 
12. 
15 
40 
7 
160 
160 
160 
13. 
c 
40 
0 
3 
14. 
6 
0 
0 
ic . 
2 
0 
0 
Total or average. 
S»oo4 
67 
55 
126 
Note .—-Temperatures during egg-laying period are included in Table I. 
