BULLETIN 261, U. S. DEPARTMENT OE AGRICULTURE. 
Table I. — Length of pupal period of wintering larvae of the plum borer, Winchester, Va. 
1913. 
Date of— 
No. of 
obser- 
vation. 
Length. 
pupal 
period. 
Pupa- 
tion. 
Emer- 
gence. 
Days. 
1 
Apr. 14 
May 17 
33 
2 
14 
15 
31 
3 
17 
15 
28 
4 
19 
16 
27 
5 
19 
21 
32 
6 
22 
21 
29 
7 
24 
18 
24 
8 
24 
21 
27 
9 
24 
21 
27 
10 
24 
21 
27 
11 
25 
24 
29 
12 
25 
27 
32 
13 
25 
27 
32 
14 
26 
27 
31 
15 
26 
27 
31 
16 
May 2 
27 
25 
17 
" 2 
27 
2-5 
18 
4 
June 2 
29 
19 
4 
May 30 
26 
20 
5 
June 2 
28 
21 
6 
2 
27 
22 
. 6 
2 
27 
23 
7 
3 
27 
Maximum . _ 
33 
24 
M 
nimum . . 
T erage 
At 
28.43 
The longest pupal period observed was 33 days, the shortest 24, 
and the average of the 23 observations 28.43 days. The records at 
Winchester show a slightly longer duration of this stage of the in- 
sect's life than has been observed by others, though data from other 
sources are rather limited. Girault, in 1905, notes that one larva 
pupated in the insectary at Washington March 28 and emerged 
April 21, a period of 24 days, while Rosenfeld, at Myrtle, Ga., in 1906, 
reports one insect that transformed from larva to adult in 20 days. 
Fred Johnson, at Youngstown, N. Y., in 1905, has the following note: 
"Larvae confined in jar form cocoons June 28. Adults emerged from 
these July 20 and others continued to appear until August 4." Evi- 
dently some of the insects in this instance transformed in less than 
23 days. The weather conditions of the spring of 1913 may be 
partially the cause of the longer pupal period at Winchester, the 
unusually high temperature prevailing through March hastening the 
insect's pupation, while the relatively cold April that followed prob- 
ably delayed the emergence of moths. 
EMERGENCE OF SPRING BROOD OF MOTHS. 
Table II gives in detail the time of appearance of 79 moths that 
emerged at Winchester in the spring of 1913 from field-collected 
rearing material. The first adult appeared in the laboratory on 
April 25 and by the fore part of May the insect was emerging in 
numbers. 
