THE BROAD-BEAN WEEVIL. 
Table V. — Number of eggs of Bruchus ruftmanus deposited on pods at Ray- 
ward, Calif. 
Date. 
Number 
pods on 
plant. 
Total 
number 
eggs per 
plant. 
Number eggs per pod. 
Maximum. 
Minimum. 
Average. 
1916. 
April 20 
12 
19 
5 
12 
14 
8 
8 
11 
10 
88 
153 
30 
70 
119 
71 
48 
115 
144 
17 
17 
18 
29 
22 
19 
9 
23 
42 
2 
1 
2 
1 
1 
4 
3 
2 
8 
7.3 
Do 
8 
6 
Do 
5.8 
Do 
8.5 
Do 
8.8 
Do 
6 
Do 
11.3 
Do 
14 
No eggs were observed by the writer except on the pods, the latter 
varying in size from less than an inch to full growth of 5 inches. 
Most of the eggs are found on the larger pods. 
Although adults have been noticed a number of times crawling over 
the plants during the day, the act of oviposition was never observed. 
It is probable that it occurs late in the evening or at night. 
Efforts to induce oviposition in captivity were not successful, so the 
total number of eggs laid by individual females was not ascertained. 
The duration of the egg stage was found to be from 9 to 18 days, 
with an average of 13 days. A few days before hatching the dark 
head of the embryonic larva can be seen plainly through the egg- 
shell. The larva draws its head back, leaving about one-quarter of 
the shell hollow. For about a day the position appears to be un- 
changed, then gradually as the larva eats through the side of the 
shell attached to the pod and into the pod the clear space in the 
shell becomes larger until the latter is entirely empty, having a 
glassy and transparent appearance. It usually takes about two days 
from the time the larva begins eating through the shell until it is 
entirely out of the latter and into the bean pod. 
The young larva begins feeding when the bean is green, and it is 
well along toward maturity before the bean dries up. The amount of 
food consumed is small compared with what other insects eat. It ap- 
pears that the young larva often eats out a short tunnel, advancing a 
little distance from the point where it entered the bean. When the 
larva gets larger it eats out a hole somewhat its own shape, and about 
50 per cent larger, as is shown in Plate I, figure 3, a and h. 
When the larva reaches maturity, and just before pupating, it eats 
out a round hole in the cotyledon, directly under the epidermis. The 
hole is plainly seen through the half-transparent skin or " window," 
which is broken easily by the adult weevil when it is ready to emerge 
(see upper beans in PI. I, fig. 5). The hole is seldom at the spot 
where the larva entered, but at varying distances from it. The 
132902°— 19— Bull. 807 2 
