21 
1977] 
Tolbert — Orb Weaving Spiders 
20 
15 
10 
5 . 
26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 
SPIDER BODY (MODEL) TEMPERATURE (°C) 
Figure 5. Number of Argiope aurantia ballooning as a function of body (model) 
temperature. 
dispersal of linyphiids, indicated that increasing litter temperatures 
were partially responsible for increased aerial dispersal by mem- 
bers of this litter-dwelling spider family. Gypsy moth ( Porthetria 
dispar L.) larvae ascend trees preparatory to aerial dispersal when 
ambient air temperatures are between 15.6°C (50° F) and 29.4° C 
(85° F). These larvae, however, have black dorsal surfaces and their 
body temperatures when exposed to direct sunlight can easily ex- 
ceed air temperatures (McManus, 1973). Thus, the aerial dispersal 
of some spider and insect species is influenced by temperature. 
Aeronautic Behavior 
In preparation for dispersal, individuals may adopt either a ’’tip- 
toe” posture, as defined by Richter (1970) or hang suspended from 
a dragline from which they become airborne (Figure 1). The tip- 
toe stance, which is widely employed by lycosid spiders (Richter, 
1970), results when the spider depresses the cephalothorax toward 
the substrate and elevates the abdomen. Silk lines are then exuded 
from the spinnerets. Multiple lines of ballooning silk were often 
