December, ’18] DAVIDSON: CALIFORNIA PISTOL CASE BEARER 
449 
Table I. Incubation, San Jose, California, 1910 
Cage No. 
No. Eggs 
Date of 
Deposition 
Date of 
Hatching 
Length of Egg 
Stage, Days 
1 
4 
May 24 
June 11 
18 
11 
25 
13 
19 
3 
25 
14 
20 
101 
1 
31 
24 
24 
1 
31 
25 
25 
3 
31 
26 
26 
2 
31 
27 
27 
1 
31 
28 
28 
102 
3 
31 
25 
25 
103 
3 
31 
25 
25 
6 
31 
30 
30 
105 
1 
31 
28 
28 
107 
3 
June 1 
30 
29 
108 
4 
1 
30 
29 
113 
29 
8 
July 5 
27 
42 
8 
6 
28 
24 
8 
7 
29 
114 
5 
June 10 
July 6 
26 
21 
10 
7 
27 
116 
6 
12 
8 
26 
7 
13 
9 
26 
1 
13 
10 
27 
12 
14 
8 
24 
7 
14 
9 
25 
1 
14 
10 
26 
1 
14 
12 
28 
11 
15 
9 
24 
5 
15 
12 
27 
19 
16 
9 
23 
7 
16 
12 
26 
Dates of Hatching. In 1910 hatching commenced about June 11 
and continued until the middle of July. In 1911 on experimental 
trees the hatching period extended until the end of July. Judging by 
the records year by year, the hatching period may be said to embrace 
the months of June and July and to reach its maximum about the 
end of June. 
Larva. Upon hatching from the egg the young larva bores into the 
leaf underneath the eggshell and thus protected, begins building its 
“case.” A silken cream-colored cylinder is first constructed around 
the body and the outside is next lined with frass and granular matter. 
When the larva is about three weeks old the “wings” of the case are 
apparent. These wings are two flaps occurring near the apex of the 
case, one on either side of the median slit. After their formation they 
are much more apparent in the young than in the old stages, and they 
stand out from the body of the case in such a manner as to give the 
whole object when viewed from above the shape of a broad arrow head. 
Later they become closely appressed to the body of the case and with 
the rounded apex tend to give to the whole the appearance of a pistol. 
The color of the young case is dark brown and opaque, while the fully- 
formed case is a grayish-black and is somewhat polished. 
The young larvae (PL 15, fig. 1) station themselves mostly on the 
under surface and skeletonize the foliage, molting once in the fall. 
They feed thus until September and during this month proceed to the 
