PREDATION BY ARGYRODES (THERIDIIDAE) ON 
SOLITARY AND COMMUNAL SPIDERS* 
By Deborah Smith Trail 
Section of Neurobiology and Behavior 
Department of Entomology 
Cornell University 
Ithaca, N.Y. 14853 
Introduction 
Species of Argyrodes Simon (Theridiidae) are best known as 
kleptoparasites in the webs of other spiders, particularly in the 
tropics (Exline 1945; Exline and Levi 1962; Kaston 1965; Vollrath 
1976, 1978, 1979). They live in or near the webs of their hosts and 
take prey from the host’s web. The methods used to take prey from 
the host vary for different species of Argyrodes and different host 
species. In some cases the Argyrodes take food which the host has 
left at the capture site or in the hub of the web. They may also take 
small trapped insects which are not normally used by the host 
(Robinson and Olazarri 1971). In other cases the kleptoparasites 
feed from prey while it is still in the jaws of the host spider 
(Robinson and Robinson 1973). 
Temperate zone Argyrodes are also found in the webs of other 
spiders, where they are generally considered to be commensal or 
kleptoparasitic. However, some temperate zone species of Argy¬ 
rodes have been observed preying on their hosts. Argyrodes 
fictilium (Hentz) was observed feeding on an Araneus sp. host 
(Exline and Levi 1962) and on Frontinella communis (Hentz) 
(Archer 1946). Lamore (1958) reported A. trigonum (Hentz) feeding 
on Mecynogea lemniscata (Walckenaer) and Wise (in press) reports 
the results of an experimental study of the impact of A. trigonum on 
a population of Metepeira labyrinthea (Hentz.) It may be that 
predation on other spiders is more important than kleptoparasitism 
for some temperate Argyrodes. This note supports that view by 
presenting observations of spider predation by two species of 
Argyrodes, A. fictilium and A. baboquivari Exline and Levi. In 
addition it compares the occurrence and predatory activities of A. 
* Manuscript received by the editor June 1, 1981. 
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