1975] 
Tolbert — Avoidance Behavior in Orb Weavers 
37 
A. aurantia, the salticid lost its grip on the Argiope’s web and body 
(?) after web flexing was commenced; the salticid (a juvenile P. 
audax ) fell onto the sticky spirals of the orb weaver’s web where it 
became entangled and was treated as a prey item (i.e. wrapped, 
bitten and fed upon). Web flexing might also distract the potential 
predator and temporarily conceal the exact location of the orb weaver. 
Stilting 
Stilting results when the spider straightens all four pairs of legs 
and thus moves the sternum and venter further away from the hub 
surface (fig. 3). The abdomen is often tilted dorsally as well; the 
spider when viewed from the ventral side appears smaller because of 
the reduced surface area exposed. This response might also change 
the sign stimulus to a shape the predator does not readily recognize 
(Riechert, personal comm.), but additional testing will be required 
before this is known. 
Dropping from web 
Dropping or jumping from the web rarely occurred in the testing. 
During the trials it was never followed by leaving the web site 
though I have observed this behavior in certain field situations. 
When a web is approached rapidly and it or the vegetation to which 
it is attached is severely disturbed, the spider may jump from the 
web and actively leave the site. When dropping or jumping from 
the web did occur under test situations and when it was normally 
observed in the field, a dragline was secured to the hub before the 
spider dropped into the vegetation. Spiders then took up a. position 
underneath a blade of grass, a leaf or along a plant stem where they 
remained for periods of less than one minute to over an hour ( A . 
aurantia N = 6, x time = 3 min. 02 seconds; A. trifasciata N = 35,. 
x time = 3 min. 11 seconds). Return to the hub was always via a 
direct, rapid climb up the dragline to the hub where a head-down 
position was assumed. If the vegetation near the spider or the spider 
itself was touched it immediately went back to the hub. Leaving 
the web is certainly an escape response and hiding underneath the 
vegetation is probably best applied against visual predators. Rapid 
return to the hub, especially when the vegetation is lightly disturbed, 
would facilitate escape if the predator was no longer in visual con- 
tact. Returning directly to the hub immediately places the spider at 
the center of its web. This may be advantageous since the orb weaver 
is back at the center of its auxiliary information gathering system, 
the web, and because most predator avoidance options are available 
at the hub. 
