1986] Opell — Web-monitoring by Miagrammopes 171 
for what initially promised to be a high percentage of spiders leaving 
the frames. The size difference made it possible to distinguish indi- 
viduals on each frame and to record which had made a web. After 
web production and position were recorded specimens were col- 
lected and released in the forest. A plot of first femur length against 
carapace length for the specimens used in this study plus the values 
of 61 additional specimens was used to assign the instar values to 
spiders. Chi-square tests were used to evaluate the results of this 
study. 
Results 
Earlier instars were more commonly found than later instars and, 
therefore, are represented by a larger sample size. Of the 21 capture 
webs constructed in the forest, nine were spun by third instars, six 
by fourth instars, four by fifth instars, one by an adult female, and 
one by a specimen of uncertain age. Of the 28 capture webs spun in 
the enclosure, four were spun by third instars, 14 by fourth instars, 
six by fifth instars, and four by adult females. Significantly more 
(0.05 > p > 0.025) spiders produced capture webs in the enclosure 
than in the forest (Table I). All capture webs made within frames 
were monitored from a moss-covered twig. In the enclosure, six 
specimens constructed their capture webs outside the frame and 
monitored them from wires used to attach frames to the support 
line. In most of these cases, the spider’s web was not anchored to a 
moss-covered twig and the highest attachment point was the favored 
monitoring site. When these six capture webs are compared with the 
other 22 indoor webs monitored from moss, moss is still the favored 
site (0.025 >p>0.01). 
In neither habitat was there a significant difference in the moss- 
covered frame sectors from which webs were monitored (Table I). 
However, these results were more clear-cut in the enclosure (0.975 > 
p > 0.90) than in the forest (0.50 > p > 0.10). In the latter setting, 
moss-covered twigs on East and South frame sectors appear to be 
favored. This may be explained by stronger and/or more unidirec- 
tional wind currents in the latter setting. On seven occasions I used a 
web dusting device to expel a cloud of corn starch into the air of the 
forest site. On three instances the wind was blowing to the east, on 
three to the southeast, and one to the southwest. These observations 
suggest that a spider’s dragline had a greater chance of being carried 
