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Psyche 
[September-December 
given this species the name el mosquero. During the rainy season, 
they take portions of communal webs from trees and place these 
in and around their homes, using them as fly traps (Berland, 1913; 
Diguet, 1909a, b, 1915; Gertsch, 1949). 
Burgess (1975) has demonstrated that vibrations within a fre- 
quency range comparable to the wing beat frequency of Musca 
domestica is the most effective stimulus for eliciting predatory be- 
havior from M. gregalis. Furthermore, the web transmits vibra- 
tions within this frequency range more readily than ones with other 
frequency characteristics. It seems that the web has characteristics 
that are particularly appropriate for the predominant prey species. 
The vibration transmission properties of webs of other species have 
not been investigated yet. 
Some Diptera may be captured when they fly into Dictyna and 
Mallos webs. However, it was noticed that many Diptera tend to 
land on the stems and leaves of herbs and shrubs, on rock ledges, 
and on other objects on which dictynids tend to build their webs. 
Perhaps the majority of Diptera are captured when they inadver- 
tently use a web as a perch. Musca domestica were frequently 
captured, seemingly in this manner, on webs of M. gregalis in the 
laboratory. These webs were kept in the open, on plants and other 
objects, in the laboratory. During routine feeding, house flies were 
thrown into the communal webs, but many inadvertently escaped 
into the room beforehand. Frequently these were seen subsequently 
landing on the webs and adhering to the silk. Thrown flies would 
seem more comparable to flying Diptera, and there is no evidence 
that the ratio of flies captured to ones that escaped differed for flies 
landing on the web compared to ones thrown into the web (Jack- 
son, 1979a). 
The extension lines in webs of M. gregalis and M. trivittatus 
may have a function related to predation. Diptera may find them 
to be particularly attractive perches and become trapped when they 
land on them. Another cribellate species, Miagrammopes (Ulo- 
boridae) has a single thread snare, and it reportedly captures Dip- 
tera that use the thread as a perch (Akerman, 1932). 
Dictynid webs have nests, which are tubular structures of more 
densely woven silk; and the spiders tend to reside in their nests 
when not active. Spiders in various families (e.g., Agelenidae, Eresi- 
dae, Dysderidae) which have nests in their webs often transport prey 
to the nest before feeding(see Bristowe, 1958; Krafft, 1971). Araneid 
