1980] 
Eberhard — Bolas Spider 
149 
her front legs actively as she moved (Fig. 10a), perhaps in order to 
sense the presence of objects beneath her future hunting site. As she 
produced the ball of sticky material at the end of the bolas line (Fig. 
lOb-d), it did not seem that she swept viscid material along a central 
line, but rather that a line as well as viscid material was pulled out 
with her IV legs. This impression was confirmed by microscopic 
examination of completed balls which showed large accumulations 
of thread (below). About 80-100 pulls with alternating legs IV were 
performed before the ball was complete, rather than 16-20 as with M. 
cornigera. Typically the spider began with shorter and quicker 
strokes, and then slowed as the ball began to form. When the ball was 
finished, it appeared that the silk simply ran out rather than that the 
spider somehow cut the line with one leg IV. The production of a ball 
took only 1-2 minutes from start to finish. 
On several occasions spiders assumed predatory positions without 
balls (Fig. 11) some of these after a ball being constructed was 
experimentally removed or became stuck to a leg and was ingested; I 
assumed that these spiders were hunting since some moths ap¬ 
proached them, but I never saw a prey capture. Hunting without first 
making a ball seemed to be associated with particularly windy 
evenings, but no careful measurements were made. 
Smaller, immature spiders made balls less often. One female which 
was an estimated 3-4 moults from maturity was seen hunting both 
Fig. 11. A mature female M. dizzydeani in hunting position without a ball, with 
both legs I extended anteriorly (seen from the side and slightly below—drawn from a 
photograph). 
