94 
Psyche 
[Vol. 87 
The webs were observed after they had been dusted with cornstarch 
to heighten contrast. If there was a possibility that the cornstarch 
could alter the feature of the web being observed, the observations 
were verified on undusted webs. The accompanying photographs are 
all of webs that have been dusted with cornstarch, and measurements 
of thread lengths were taken from similar calibrated photographs of 
dusted webs. 
Habitat. The Wendilgarda species we observed occurred above 
streams flowing through relatively flat areas of wet tropical forest. 
The streams were of moderate size, usually 3-4 m across, and 0.3-0.6 
m in depth. Flow rates at the surface of Quebrada el Sura at La Selva 
averaged 2.8m/sec (S.D. =0.02 m/sec) on the days we observed the 
webs. The webs themselves were found at the edge of the stream or in 
the lee of a protruding snag in the stream where the flow rate is 
considerably less, averaging 0.13 m/sec (S.D. = 0.03 m/sec) at La 
Selva. Web architecture. As far as we know, the webs of Wendilgarda 
species are qualitatively indistinguishable in the field, and so our 
comments apply equally to any of the populations we observed. Each 
Wendilgarda web (Fig. la-c) consisted of a variable number of 
interconnecting, more or less horizontal lines of non-sticky silk. The 
horizontal lines connected in a dendritic pattern; closed polygonal 
cells of the sort typical of most other spider webs were never 
observed. The free ends of the horizontal lines attached directly to 
substrates in the web site, such as leaves or branches of overhanging 
plants, or woody debris in the stream itself. The webs did not have 
“frame lines” such as are typical of the orb-webs of other theridioso- 
matid genera or araneid spiders. An entire functional web may 
contain only one such horizontal non-sticky line or as many as six; 
the average number was three (n = 14 webs). The height of the 
horizontal lines above the stream surface ranged from 10 to 39 mm. 
They varied in length from 23 to 160 mm, averaging 86 mm (n = 22 
horizontal lines). Occasionally the center of the web, or where the 
usually three horizontal lines intersected, was supported from 
vegetation above by one or two “guy lines” (Fig. la), but many of the 
webs occurred in sites with no objects immediately above the web, 
and, hence, with no guy lines to the web center. Usually the spider 
hung ventral side up on accessory lines at the periphery of the web, or 
hung suspended from the junction of two or more horizontal lines 
(Figs, la, lb, 3a). 
