272 
Psyche 
[Vol. 91 
• TOTAL POPULATION,* — -•' 
o SPIDERLINGS < 2r 
1980 
ION,* 
nm/ 
0 
300- 
200 - 
-o --o' 
198 1 
*-^8 o, 
.■a^r-a -T- a- . X 
□ ADULT dV r-| 
■ ADULT 9 ? n U 
Ml.-lll. 
APR MAY JUN JUL AUG SEPT OCT 
Figure 1 . Seasonal and yearly changes at the Liberty site in density of spiderlings, 
adults and all stages combined. Numbers on the 13 marked areas are pooled. 
Changes in numbers are directly related to changes in population density because 
these same areas were censused each date. Although censuses were not conducted as 
frequently in 1982, they were made often enough to reveal a pattern similar to that of 
previous years: scarcity of adults at the end of June and an increase by early August. 
and summer in number of eggs reflected seasonal differences in 
female size and egg size. However, the eggs laid by summer females 
were significantly larger than spring eggs even after correction had 
been made for the negative correlation with egg number (Table 2). 
The correlation between mean egg diameter and mean hatchling 
size for 46 summer females in 1982 was 0.51 (p < .001, df = 44). 
The structures of the Liberty and Patuxent populations differed 
on the same date (Fig. 3). Peaks in adult abundance occurred earlier 
