350 
Psyche 
[Vol. 87 
fictilium, A. baboquivari and A. subdolus O. P.-Cambridge in the 
webs of solitary and communal spiders. 
Methods 
These data were collected during a field study of social behavior 
of Philoponella oweni (Chamberlin) (Uloboridae) in South Fork 
Canyon (1979 and 1980) and Herb Martyr Recreation Area (1980) 
in the Coronado National Forest in the Chiricahua Mountains, 
Cochise Co., Arizona, from June through September 1979 and July 
1980. 
In 1979, approximately 100 P. oweni web sites, occupied by 
solitary females or by communal groups of females with intercon¬ 
nected webbing, were examined 2-5 times per week. Philoponella 
oweni is facultatively communal. That is, in one habitat both 
solitary individuals and communal groups can be found. During 
each census I recorded the number of Philoponella present at the 
web site as well as presence and activities of Argyrodes. In most 
cases the Argyrodes were collected as soon as they were found. 
When Argyrodes were observed in the webs of non-uloborid 
spiders, this too was noted. 
Results 
Argyrodes were observed in the webs of other spiders on 14 of the 
census days, covering a period from June 20 to September 18. 
Argyrodes fictilium were observed in the webs of other spiders on 3 
occasions, each involving predation on the host species: hatchlings 
of P. oweni, a large Frontinella species, and a second, unidentified 
linyphiid. Predation by A. baboquivari was observed in seven of 19 
sightings in webs of P. oweni. Both adult male and female A. 
baboquivari were seen preying on adults, immatures and eggs of P. 
oweni. 
In July 1980 three specimens of A. subdolus were collected: one 
from the web of a solitary P. oweni and one from the webbing of 
each of two communal groups of P. oweni. Since A. subdolus was 
rarely seen, and since no feeding behavior of any sort was observed, 
these three observations were not included in later calculations. 
The occurrence of Argyrodes in the webs of P. oweni and 
predation rates on the host were calculated for solitary and com¬ 
munal P. oweni. Even though only 28% of the web sites, on average, 
