1984] 
Wise — Phenology of filmy dome spider 
277 
Table 3. Web-site temperatures. Means ± s.e. with number of web sites measured 
in parentheses. 
Shady Sites 
Sunny Sites 
Patuxent 
Liberty 
Patuxent 
Liberty 
24 May 
20.2 ± .2 
18.6 ± .1 
21.8 ± .6 
19.6 ± .2 
(30) 
(57) 
(10) 
(4) 
8 June 
24.8 ± .3 
23.5 ± .1 
27.2 ± .4 
24.1 ± .3 
(13) 
(54) 
(7) 
(14) 
first feeding round each day, suggesting that the majority of imma- 
ture spiders was not experiencing a shortage of prey. 
Many adults that appeared during the experiment undoubtedly 
were immigrants, as were some of the juveniles present in Sep- 
tember. However, a significant fraction of the immature spiders on 
the units in September was likely part of the original cohort, since 
small spiders that were obvious immigrants were removed continu- 
ously during the experiment. Clearly many adults were immigrants, 
as the number appearing exceeded the decline in number of imma- 
ture spiders. However, substantial numbers of penultimate stages 
appeared on the units during the first few weeks, indicating that 
many of the adults did develop from spiders that had been added to 
the units. Thus the immature filmy dome spiders added to the units 
in July apparently had one of two fates. Some matured by August 
or September, whereas the remainder were still immature by the 
middle of September and would not mature until the following 
spring. 
Rearing Studies: Field-Collected Juveniles 
All 47 juveniles removed from the population at Liberty in 1980 
had matured by the end of August. These appeared to have been 
stage 3 or older when collected on 1 July. 
The following year not all survived to the end of the summer, 
probably because smaller instars were collected. Over half (65%) of 
the immatures collected in 1981 did survive, and all were adult by 
the end of August (Fig. 5). 
In 1982 the populations were sampled 2 weeks later in July. Many 
of these juveniles had not matured by the end of the season. The 
total number that had either matured or were still alive as imma- 
tures by mid-September was 106 (86% of the number collected); 
39% of these spiders were still immature. The developmental status 
