8 
BULLETIN 807, U. S. DEPARTMENT OF AGRICULTURE. 
The cost of hand picking to remove the weevily beans also de- 
pends on the degree of infestation, but it is estimated at about $1.50 
per 100 pounds. 
Estimates of the reduction on the total horse bean acreage, because 
of the increase in weevil infestation, range from 25 to 75 per cent. 
Alameda County was formerly the largest producer, but at present, 
due largely to the extensive infestation of all horse beans grown there, 
practically no beans are produced commercially. It is also estimated 
that if weevil infestation could be prevented, the acreage for the dry- 
bean crop alone would be increased from 100 to 300 per cent in that 
county. 
It will be seen from Table III that there is considerable varia- 
tion in the percentage of infestation in the different districts. There 
is also great variation in the number of weevils developing in a single 
bean. In the case of the pea weevil B. pisorum (fig. 3), with a A^ery 
similar appearance and life history, only one weevil develops in a 
seed, but with the broad-bean weevil there are often two and three 
adults in a single bean, while it is not at all rare to find four, five, and 
even six. The followinof table illustrates this : 
Table IV. — Summary of the percentage of broad beans infested with different 
number of iveevils. 
Number beans examined. 
Locality 
raised. 
Year 
raised. 
Num- 
ber 
weevils 
per 
bean. 
1 wee- 
vil per 
bean. 
2 wee- 
vils per 
bean. 
3 wee- 
vils per 
bean. 
4 and 5 
weevils 
per 
bean. 
Total 
per 
cent 
infested. 
1,000 
Havward 
do 
do 
Stockton 
Hayward 
1915 
1916 
1917 
1917 
1917 
371 
331 
781 
880 
573 
367 
324 
164 
105 
227 
186 
216 
46 
14 
140 
63 
95 
9 
1 
29 
13 
34 


31 
62.9 
1,000 
1,000 
1,000 
66.9 
21.9 
12 
1,000 
42:7 
I 
58.9 
23.7 
12 
3.9 
1.5 
41.1 
1 
LIFE HISTORY. 
The eggs are laid on the outside of the green pods, being cemented 
to the latter b}^ a glutinous secretion. They are laid singly and in- 
discriminately over the surface of the pods (see PL I, fig. 1) without 
apparent reference as to whether the position is favorable or un- 
favorable to the newly hatched larva getting into the young bean. 
The number of eggs on a pod also bears no relation to the number 
of beans it contains, as often the former exceeds by many times the 
number of larvae which might develop therein. One pod 4 inches 
long was observed with 55 eggs deposited on it. The following table 
shows the variation in number of eggs laid on a pod. 
