1985] 
Eberhard — Orb web of Eustala 
109 
ered the next radius (the one along which it had just moved to the 
frame), and the cycle just described was then repeated (Fig. 2). 
When moving outward along radii that were attached directly to the 
substrate instead of to a frame line, the spider omitted the “back- 
ward” segment of the behavior, and simply returned inward along 
the radius, producing a spiked rather than sawtooth pattern of 
sticky line. 
Sticky line construction terminated when the spider encountered 
a sticky line it had already laid, and the sticky lines were thus laid in 
a single 360 degree trip around the web. The spider then moved to 
the hub of the web and finished web construction by removing the 
small mesh of lines inside the hub loops, just as do many other 
araneids (Eberhard 1982). 
Webs of very small nymphs 
Two nymphs were found on complete, typical orb webs, one in 
the center of such a web (Fig. 3), and the other crouching in a typical 
retreat (see below) that was connected to a nearby orb of similar 
design. Construction behavior of these spiders was not observed. 
Immature spiders are generally difficult to identify, but these 
nymphs had the same unusual combination of characteristic white 
abdomens, white cephalothoracic markings, and dark pink prolat- 
eral surfaces on their legs and were of the same size and shape as 
others that emerged in captivity from egg sacs found with adult 
females. The nymphs with webs occured on the same Heliconia 
leaves where I found four other individuals (two mature females) of 
Eustala sp., and they had the same unusual retreat design as the 
older spiders (below). Thus the nymphs’ identity is fairly certain 
despite their lack of diagnostic genitalic characters (voucher speci- 
mens are deposited in the Museum of Comparative Zoology in 
Cambridge, Mass.). 
Retreats 
The retreats, which are apparently unique among araneids in their 
design, were on the undersides of leaves (Fig. 1). The spider sat in 
the bottom of an inverted truncated cone-like structure, pressing its 
body flat against the leaf. The flared sides of the cone, which were 
supported by a small, inconspicuous meshwork of threads had 
