230 
Psyche 
[September-December 
In Panama a web of the araneid spider Cyrtophora nympha 
Simon, collected in July 1976 on the Navy Pipeline Road, Gamboa, 
Canal Zone, contained a single caterpillar moving about in the web 
in the same way as the larvae in the Anelosimus colonies. This was 
collected together with the web and the host. The caterpillar is 
shown in Figure 2. It disappeared without trace. 
Finally, F. Vollrath reports (pers. comm.) that he found a cater- 
pillar living in the web of a diplurid and feeding on prey remains; 
it also apparently fed on the web silk, where it made “dime-sized 
holes.” Neither the diplurid nor the moth have been determined. 
Discussion 
So far all the associations between lepidopteran larvae and 
spiders occur where the hosts build webs that persist for long 
periods at the same site. This is certainly true of Stegodyphus 
and Anelosimus colonies and also true of Cyrtophora nympha. 
The webs of the latter are presumably high investment structures 
like those of C. moluccensis (see Lubin, 1973, 1974); they are soli- 
tary and become littered with leaves and debris and often look 
defunct. An indication of the persistence of C. nympha webs is 
given by the fact that colonies of Uloborus republicanus often es- 
tablish themselves in the upper snare (personal observations). In 
Panama, ground-living diplurids build their sheet webs at one site 
for long periods and have a wide range of arthropod commensals, 
kleptoparasites and other symbionts (Vollrath, Kirkendall, pers. 
comm.). The correlation between persistent webs, or persistent 
utilization of web sites, and the occurrence of lepidopteran sym- 
bionts suggests that the webs of other perennial (or long-term) 
web-site occupiers should be examined for caterpillar cohabitants. 
The various gregarious Cyrtophora species are clear candidates for 
such studies. 
Another factor is necessary to provide a niche (within a web) for 
scavenging cohabitants: clearly there must be an accumulation of 
prey-remains. If prey-remains were rapidly ejected from the web, 
there would be no resource for a scavenger to exploit; kleptopara- 
sitism or commensalism would be the only feeding niches available 
to symbionts. 
