EGGCASE CONSTRUCTION AND FURTHER 
OBSERVATIONS ON THE SEXUAL BEHAVIOR 
OF THE SPIDER SICARIUS (ARANEAE: SICARIIDAE)* 
By Herbert W. Levi and Lorna R. Levi 
Museum of Comparative Zoology, Harvard University 
The eggcase of Sicarius is unique among spiders. Its masonry wall 
resembles in texture the nests of mud dauber wasps. And, unlike 
other spider eggcases, it is buried in sand, attached to stones. We 
do not know of any other masonry construction by spiders, or of 
other buried eggsacs. Some spiders incorporate sand grains and 
detritus into their webs or their trapdoors. The European, theridiid 
Achaearanea saxatile (C. L. Koch) makes a thimble-shaped retreat 
for herself and her silken eggsac (Potzsch, 1963), and covers the 
thimble with large sand grains and little stones. The colonial 
European zodariids, Zodarion germanicum (C. L. Koch) and Z. 
elegans Simon, build retreats under stones. Each semispherical 
retreat is covered by sand grains from the surroundings, and pieces 
of bark and spruce needles are woven into the wall. The retreat is 
used by the spider and the eggsac is hung up in it. As far as I know, 
the building of the retreat has not been observed. Wiehle (1953) 
illustrates a row of large setae in front of the zodariid spinnerets and 
peculiar branched setae that cover the legs and tarsi. These setae are 
perhaps used for handling the detritus. 
The unusual Sicarius eggcase was first noted by Simon ( 1899) 1 . Al- 
though we have two species of Sicarius in culture the possibility of 
watching eggsac construction seemed at first remote because the only 
eggcase made in the laboratory appeared to have been constructed 
while the spider was covered by sand. 
Sicarius belongs to a small family of little-studied spiders, dis- 
tributed in the southern hemisphere and related to the more wide- 
spread Loxoscelidae and Scytodidae. Any behavior observations are of 
phylogenetic interest. The several species of Sicarius inhabit deserts 
and bury themselves in the sand (Reiskind, 1966.) The burying, 
the material of the eggcase and the burying of the eggcase are probably 
adaptations to avoid extreme heat. The spiders presumably evolved 
*The research was supported in part by Public Health Service Research 
Grant AI-01944 from the National Institute of Allergy and Infectious 
Diseases. Manuscript received by the editor October 4, 1968. 
J Biraben (1939) reported and described the egg cases for Argentinian 
species. 
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