THE BROAD-BEAN WEEVIL. 
19 
Table XV. — Comparing the degree of weevil infestation in horse beans from 
all districts in California, planted in different months. 
Year. 
Oct. 
Nov. 
Dec. 
Jan. 
Feb. 
Mar. 
Apr. 
May. 
1916 
Per cent. 
46 
Per cent. 
47 
50 
30.1 
Per cent. 
15.2 
15.6 
19.1 
Per cent. 
14.4 
17.5 
18.5 
Per cent. 
5.2 
8.21 
15.7 
Per cent. 
9.6 
12 
12.9 
Per cent. 
1. 
Per cent. 

1917 
1918- - 
4.3 
.8 
42.3 
16.6 
16.7 
9.7 
11.5 
' 2.6 
.4 
To test this out further, plantings of horse beans were made at 
Pasadena, Alhambra, and Hayward, for the years 1917 and 1918, 
in which a certain number of beans were planted each month, and 
when harvested carefully examined to find out the percentage of 
infestation. The results are given in Tables XVI and XVII. 
Table XVI. — Shoiving the percentage of weevil infestation of beans planted 
during certain months at Pasadena and Alhambra. 
Year. 
Nov. 
Dec. 
Jan. 
Feb. 
Mar. 
Apr. 
May. 
1917 ! 
17 
45 
11.5 
15.5 
12 
8 
7.5 
. 75 
5. 
2.6 
1918 
43.5 
i Degree of infestation for 1917 crop found by counting larval entrance holes, which are about 50 per cent 
greater than number of adult weevils. 
Table XVII.— Showing the percentage of infestation of beans planted during 
certain months at Hayward, Calif. 
Year. 
Nov. 
Dec. 
Jan. 
Feb. 
Mar. 
Apr. 
May. 
1917 
24 
14 
18 
5 
9.6 
9.3 
1918 
74.5 
67.5 
32 
These tables clearly show that the later in the season the seed is 
planted the lower the percentage of infestation will be, A possible 
explanation of this may be found by referring to the seasonal history 
of the insect, which shows that egg laying begins about the middle 
of March, is heaviest in April, and extends to the middle of May. 
Figure 5 shows also that at Hayward the first adults were observed 
in a broad-bean field on March 18 and that the number constantly in- 
creased each week to May 4, after which the number decreased as 
constantly until June 15, the last date any were observed. Since the 
eggs are laid only on the pods, it follows that any plants which pro- 
duced pods prior to or during April will be subject to the greatest 
egg deposition, and pods produced subsequently to the latter part of 
April would be liable to little or no egg deposition. 
Seed planted from October to February begins setting pods in 
March and April, while seed planted from the latter part of February 
to May will begin setting pods from the latter part of April to June. 
