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Wise — Phenology of filmy dome spider 
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to develop. Many females continued to feed and deposited addi- 
tional sacs. However, because the frequency of multiple clutches in 
nature is unknown, data are given for the first sac only. 
Temperatures of web sites were recorded concurrently at Patux- 
ent and Liberty with thermocouple probes on 24 May and 8 June, 
1983. Each probe was covered with black tape, so that its tempera- 
ture closely approximated the internal temperature of a filmy dome 
spider exposed to solar radiation (personal obs.). Sites selected for 
recording temperature originally had a N. radiata web and, as a 
group, spanned the range of exposure to wind and sunlight of webs 
at each study site. 
Direct Evidence for Different Rates of Development 
Field Experiment 
During the last half of the season, N. radiata populations charac- 
teristically contain all stages. This diversity makes it difficult to 
follow the growth and development of groups of juveniles. There- 
fore, a manipulative field experiment was designed to facilitate mon- 
itoring of the developmental pattern of the younger spiders in the 
population. 
Eight experimental units were placed at least 10 m apart in the 
undergrowth at Patuxent. Made of wood stakes that supported 
undulating pieces of 5.1 cm-mesh galvanized wire fencing (chicken 
wire), each unit was 3 m long, 1 m wide and 1 m high. Use of these 
standardized units made it possible to establish open, replicated 
populations of similar densities and microclimatic conditions, and 
also facilitated identification of the experimental populations. 
From 8-17 July 1981, filmy dome spiders were removed from the 
units and from surrounding vegetation. The smaller instars, all of 
which had emerged from egg sacs laid by spring-maturing females, 
were then added at random to the cleared units. On 21 July (Day 0 
of the experiment) each unit contained 20-39 spiders (x = 30 ± 2), 
all estimated to be stages 2-4. This range represented the youngest 
instars in the Patuxent population on that date. 
Four randomly selected populations received supplemental prey 
from 21 July through 28 August. On 21 days each spider was given a 
living fruit fly; on 5 of these days each spider was given another fly 
during a second round of feeding. 
The 8 populations were censused frequently. At each census all 
mature spiders were removed and measured. Very small spiders that 
were obvious immigrants were also removed. Censusing of all units 
