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[Vol. 87 
prey with one leg IV, climbed onto the trapeze line, and turned the 
moth so its anterior end was at her mouth and fed. 
Several variations on this general scheme were observed. On some 
occasions a spider which had captured a moth did not feed 
immediately, but fastened it to the trapeze line, spun a new ball, and 
resumed hunting; in one case a spider had three prey on the trapeze 
line when she caught a fourth. Longman (1922) observed a Dichro- 
stichus magnificus which also temporarily stored prey on the trapeze 
line. In no case did I see an extended coating along the bolas line as 
has been observed with M. bisaccata (Gertsch 1955) and D. 
magnificus (Longman 1922), and only one of an estimated 60 balls 
observed was double. On one occasion however I saw an even 
stranger trap. One particularly warm and windless evening a spider 
had an unusually long trapeze line which had three different balls 
hanging from it. The spider was at one end of the trapeze in a 
predatory stance, and did not hold a ball. The spider soon ate the 
balls, and later the same night made a single ball and held it with one 
leg in the usual fashion. 
Balls were ingested if after a period of waiting no prey were 
captured; such lapses averaged 24 min (range 14-41, N=8). Usually 
the spider did not make another ball immediately after ingesting an 
earlier one, but rested immobile for up to an hour or more. 
The Ball 
Moths are difficult prey for web spiders to capture since their 
abundant and easily detached scales more or less insulate them from 
sticky traps (Eisner et al. 1964), and some araneids have evolved 
special attack behavior towards them to offset this defense (Robinson 
1969, Robinson, Robinson and Graney 1972). It is thus surprising 
that M. dizzydeani was able to catch moths regularly with a sticky 
trap, and the structure and function of the sticky ball assume 
particular interest. 
The balls of M. dizzydeani were largely liquid. When touched to a 
piece of filter paper, a ball immediately wet an area two to three times 
its diameter and, to the naked eye, disappeared. When touched to a 
nonabsorbant object like a glass slide, the ball remained visible as a 
mass of jelly-like material surrounded by a pool of liquid (Fig. 13). 
That the ball’s wetness is essential to its stickiness was shown by 
taking a newly made ball away from a spider and letting it hang free at 
