SANITARY BEHAVIOR BY THE SOCIAL SPIDER 
MALLOS GREGALIS (DICTYNIDAE): DISTRIBUTION 
OF EXCRETA AS RELATED TO WEB DENSITY AND 
ANIMAL MOVEMENTS.* 
By William J. Detjen 
Department of Biology 
Georgia College 
Milledgeville, Ga 31061 
Introduction 
The organization of colony behavior by gregarious animals 
depends not only on the behavioral repertoire observed in individuals 
but also on physiological limitations evolution has imposed on the 
species. Such physiological restraints extend to the elimination of 
metabolic wastes by individuals which can affect the distribution of 
nutrients and parasites in the immediate environment (McBride, 
1976). These by-products, in addition to prey remains, can have 
important consequences related to nest sanitation in social units of 
low vagility. In addition, metabolic wastes may perform a secondary 
communicative function in some species (Tietjen and Rovner, 1981). 
Mallos gregalis Simon is one such group-living species of spiders in 
which thousands of individuals of both sexes and various age groups 
occupy a semi-permanent web (Burgess, 1976; Diguet, 1908, 1915). 
To avoid fouling of such a long-term web site, one might expect 
sanitary behavior in such species. Unlike Agelena consociata, 
however, which exhibit nest-cleaning behavior by removing prey 
remains from the web (Krafft, 1969), M. gregalis do not remove 
carcasses, but incorporate prey remains into the nest structure 
(Jackson, 1978). Tietjen (1981) suggested that M. gregalis did not foul 
the web with fecal material, but eliminated wastes near the edge of the 
web. This produced a ring of excreta which surrounded the web site. 
These conclusions were, however, based upon observational, rather 
than experimental data. An alternative explanation can explain the 
observed ring of excreta: If M. gregalis utilize mainly the upper surface 
of the web they may deposit excreta uniformly over the web surface. 
If the excreta are incorporated into the web structure as are prey 
* Manuscript received by the editor September 8, 1980. 
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