1980] 
Jackson — Dictyna & Mallos 
217 
Dependence on conspecifics for survival seems more pronounced 
for the males of M. gregalis than for the females and immatures. 
Although individuals of M. gregalis normally feed and construct 
their webs in groups, females and immatures have functional cribella; 
and they can construct and use adhesive webs to capture insects 
alone. Thus, males of M. gregalis died more frequently than females 
and immatures of this species when in their own webs (Table 2). 
Few males of M. gregalis died when kept for 30 days with females 
(Table 3); and often they were observed feeding, alone or with the 
females, on both Musca and Drosophila. When alone in webs built by 
females, few of the males provided with Drosophila, but many of 
those provided with Musca, died. Musca often adhered to the webs; 
but unlike the Drosophila, they usually struggled violently; and the 
males were sometimes seen running from them. With females present, 
males were seen joining the other spiders to feed on Musca whose 
struggles had begun to subside but not to begin feeding alone on 
struggling flies. Possibly at least a partial explanation for the 
differences in survival in Table 3 can be found in this cautious 
behavior of the males. 
Table 2. Adult males, adult females, and immatures of Mallos gregalis maintained 
for 30 days with either Musca domestica or Drosophila melanogaster provided as a 
prey. G-tests of independence, with Yates Correction, carried out separately for 
survival rates of those provided with each of the two types of prey: P < 0.001. 
Prey 
Sex/Age Class 
Number of Spiders 
Survived Died Total 
G 
Males 
12 
8 
20 
Musca 
Females 
20 
0 
20 
13.110 
Immatures 
16 
4 
20 
Males 
21 
14 
35 
Drosophila 
Females 
19 
1 
20 
12.226 
Immatures 
18 
2 
20 
