6 
Psyche 
[March 
different reasons. As an early spring insect, P. n. microstriata trades 
off lateness of emergence (to reduce the probability of catastrophic 
weather-induced mortality) against earliness (to match the phenol¬ 
ogy of the vernal Crucifers). The former factor would seem more 
compelling at Lang, the latter at Gates. How do P. n. microstriata 
“decide” when to emerge? 
Under controlled laboratory conditions populations show an 
astonishing intrapopulational variance in the chilling requirement 
to break pupal diapause. There seem to be interpopulational differ¬ 
ences as well, but for the purposes of Table 3 pupae from four 
Table 3. “Chilling requirement” to break diapause in P. n. microstriata. Dormant 
pupae were held at 3° C and tested at intervals at 20° to ascertain whether diapause had 
been broken. Pooled data for several broods (see notes), 1972 through 1978. 
Number of weeks 1 
Genetic diapausers 1 
Number of Percent 
Facultative diapausers 2 
Number of Percent 
held at 3° prior 
pupae 
of all 
pupae 
of alt 
to activation 
activating 
pupae 
activating 
pupae 
5- 9 
12 
2.9 
0 
0 
10-14 
14 
1.0 
9 
9.2 
15-19 
9 
2.2 
30 
30.6 
20-24 
11 
2.7 
24 
24.5 
25-29 
49 
12.1 
13 
13.3 
30-34 
78 
19.3 
8 
8.2 
35 39 
1 11 
21A 
' 5 
5.1 
40-44 
37 
9.1 
1 
1.0 
45-49 
41 
10.1 
1 
1.0 
50-54 
15 
3.7 
0 
0 
55-59 
3 
0.7 
0 
0 
60-64 
7 
1.7 
0 ' 
0 
65-69 
3 
0.7 
1 
1.0 
70-74 
' 8 
2.0 
0 
0 
75-79 
4 
1.0 
0 
0 . 
greater than 79 
13 
3.2 
6 
6.1 
notes: 
'defined as individuals which diapaused under continuous light at 20° C+ 
. From 14 
females ex 3 foothill populations and 1 
^defined as individuals which diapaused 
mid-elevation Sierran population 
under inducing photoperiods at 20° 
C+. Since 
these broods included some genetic diapausers which would have diapaused anyway. 
these are included in the tally. From 4 females ex 2 foothill populations. 
’time elapsed does not include pre-testing time and testing time to assess dormancy at 
20°. 
