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Psyche 
[Vol. 94 
tropical, M. gracilis ranges into temperate North American decidu- 
ous forests east of the Rocky Mountains (Levi 1985). This spider 
builds an orb web within a rectangular or triangular silk frame 
which is typically located 1-3 m high and spans large open spaces in 
the forest understory. The orb portion of the web is removed in the 
evening and rebuilt at dawn. The frame, however, may persist at the 
same site for many days. In the southeastern United States M. 
gracilis reaches maturity by mid-to-late July. There is extreme 
sexual dimorphism, and upon reaching maturity males cease 
building webs. Therefore, adult females were used in this study, 
since they maintain webs throughout the summer, and these webs 
are crucial to survival and egg production. 
Release experiments 
This study was conducted during July and August 1983 in a for- 
ested area which included a transition zone from an open pine stand 
to a deciduous forest. The privately-owned site was located in 
Griffen, Georgia (4.5 miles W. of the Spalding Co./ Butts Co. line). 
Canopy tree species in the deciduous section were Quercus velutina 
Lam., Q. nigra L., Acer rubrum L., and Pinus taeda L. The pine 
stand consisted of mature P. taeda, young P. taeda (< 2m tall), Q. 
nigra and Rubus sp. (both < lm tall). The pine stand was bordered 
on one side by the deciduous area; the opposite side was bordered 
by a row of small pine trees, beyond which was a grape arbor; a dry 
ditch and a paved road ran along one side, and opposite this was 
continuation of pine forest. The deciduous forest area was also 
bordered by the road, and the two other sides were a continuation of 
deciduous habitat. 
Release experiments were conducted in a 32 X 32 m plot encom- 
passing both pine and deciduous forest. Each square meter of the 
study plot was assigned a number corresponding to numbered flags 
which bordered the area at 1 m intervals. Prior to initiation of spider 
manipulations, the height of all vegetation in each square meter of 
the study plot was measured, and the presence or absence of pine 
canopy and deciduous canopy was recorded. 
All of the adult female M. gracilis present were collected from the 
study plot and the surrounding area (n = 24). Spiders were marked 
by affixing newsprint letters to the dorsal surface of the abdomen 
with clear nail polish, providing each with a unique letter identity, 
