278 
Psyche 
[Vol. 91 
DATE 
Figure 4. Numbers of immature spiders present in webs and cumulative numbers 
of adults removed during the 1981 field experiment. Not included are the obvious 
immigrants: juveniles smaller than those that were present the previous census (these 
were removed) and adults that appeared during the first week. 
of spiders at this time of the season accurately predicts their state of 
maturity at the end of the season for two reasons: 1) In nature newly 
matured spiders do not appear after mid-September; 2) all but one 
of the immatures collected in 1982 that did mature that season 
completed the adult molt by 25 August. The one exception was a 
female that matured on 9 September. 
When collected in July, juvenile spiders from Patuxent were more 
developed than those collected from Liberty and were more likely 
to have molted to adulthood by September (Fig. 6). A signifi- 
cantly greater proportion of the spiders from Patuxent was mature 
(31 / 4 1 = .76) than from Liberty (34/65 = .52) (x 2 = 5.76, p < .05). 
The mean date on which the spiders molted to the adult stage was 6 
August for those from Patuxent and 15 August for the Liberty 
spiders. Although spiders that were larger when collected were 
more likely to have matured, the correlation with stage and future 
