1978] 
Jackson & Smith — Mallos and Dictyna 
67 
changes in their positions before they could be recorded. Only the 
component of the web (nest, mesh, interstitial web) occupied by the 
spider could be recorded with confidence. When counting the 
number of spiders per web unit, those in the interstitial web were 
included in the record of the web unit to which they were in closest 
proximity. 
Spacing and density data were not collected for D. albopilosa. 
The web complexes of this species were particularly difficult to 
disassemble in the field because they were three-dimensional and 
located on the leaves, stems and roots in dense growths of herbaceous 
plants. Those of D. calcarata and M. trivittatus, in contrast, were 
two-dimensional and usually built on more accessible flat surfaces. 
At San Anton Falls (Morelos, Mexico), 23 occupied web units of 
D. albopilosa were searched, and the occupants were recorded, with 
no attempt to assess density or spatial relations. In addition to the 
spiders in the census areas, the occupants of another 48 web units of 
D. calcarata and 152 of M. trivittatus were recorded. Each of these 
was in the general vicinity of the census areas. 
Data for M. trivittatus were collected in June; those for M. 
niveus, D. calcarata, and D. albopilosa were collected in September. 
These species seem to feed predominantly in the late afternoon and 
early evening (Jackson, 1977a). Data in this study were collected at 
mid-day, when the spiders were less active. 
LABORATORY STUDIES — Mallos gregalis 
In the laboratory, M. gregalis in large communal webs were 
maintained on a diet of houseflies (Musca domestica), provided at 
approximately 5-day intervals. Temperature was maintained at 
approximately 24° C, and the light cycle was approximately 13 L: 
11D. These large colonies were begun from fewer than 200 spiders 
collected by Burgess (see Burgess, 1976) in Guadalajara, Mexico, 3 
yr previous. The webs in the laboratory were on plants and other 
objects, and they were not enclosed. 
Two census methods were used. 1. Small discrete communal webs 
and relatively discrete portions of larger communal webs were 
completely disassembled in the spring and early summer. All occu- 
pants were recorded; and the condition, structure, and size of the 
webs were recorded. 2. The surface of a large communal web, at 
least 2 years old, was censused with 30cm transects in the fall. Each 
transect consisted of a string laid haphazardly onto the web, and all 
