74 
Psyche 
[March 
A related comparison can be made by looking at the amount of 
web area or volume per individual spider for different species. There 
is a trend toward decreasing web surface per spider as one goes from 
solitary to communal species. Individual webs of solitary species 
tend to have a surface area of 35 cm 2 (Jackson, 1978a). Since each 
web unit in web complexes of communal, territorial species tends to 
contain 2 or 3 spiders (Table 3), and since web units tend to have a 
surface area of 4 to 21 cm 2 (Jackson, 1978a), there tends to be 1 to 7 
cm 2 of surface area per spider in these species. In the laboratory, in 
communal webs of M. gregalis, there tends to be a surface area of 
2.1 cm 2 and a volume of 6.4 cm 3 of web per spider. (Volume was not 
calculated for other species since their webs tended to be largely 2- 
dimensional; Jackson, 1978a.) 
The influence of prey availability on these trends deserves atten- 
tion. Diptera of the same approximate size relative to the spider 
seem to predominate in the diet of species of Dictyna and Mallos 
Table 3. Percentages of web units (in web complexes) occupied by different sex/ 
age class combinations. Data based on nests alone ( M . trivittatus ) given in paren- 
theses. More than one immature sometimes occurred together in same web unit. 
More than one adult of same sex never occurred together. N: No. of web units 
sampled, including ones in Table 1 plus others (ones not occupied by dictynids 
excluded). 
M. trivittatus 
D. calcarata 
D. albopilosa 
Females' 
33.33 (34.15) 
30.30 
39.13 
Males' 
7.58 (4.07) 
24.24 
21.74 
Immatures' 
84.09 (75.61) 
77.24 
65.22 
Female Only 
14.39 (20.33) 
7.58 
21.74 
Male Only 
0.76 (1.63) 
9.09 
8.70 
Immatures Only 
61.36 (61.79) 
56.06 
47.83 
Female plus Immatures Only 
16.67 (13.82) 
12.12 
8.70 
Female plus Male Only 
0.76 (0.00) 
9.09 
8.70 
Male plus Immatures Only 
4.55 (2.44) 
7.58 
8.70 
Female, Male, and Immatures 
1.52 (0.00) 
1.52 
0.00 
No. of Spiders per Web Unit 2 
3.1 ± 4.83 (20) 
1.6 ± 0.91 (4)3 
1.3 ± 0.47 (2)3 
N 
132 (123) 
66 
23 
'Regardless of other sex/ age classes present. 
2 Mean ± S.D. (maximum). 
3 Larger maxima were seen during more casual observations. 
