492 
Psyche 
[December 
position is reversed in the upper part of the web. There, prey car- 
ried on silk would tend to hang awkwardly against the spider’s body 
or legs. Argiope argentata does not carry prey from the upper part 
of the web on silk. Prey of a weight which would be carried on silk 
in the lower web are often carried in the jaws from the upper web. 
Very heavy prey, in the upper web, are moved to the hub, after 
wrapping, by a complex process which has been called the “derrick 
technique” (Robinson & Olazarri, in press). Thus the role of post 
immobilization wrapping, at the capture site, in facilitating transpor- 
tation, is probably most clearly illustrated by consideration of activities 
in the lower part of the web. Transportation of prey with long and 
projecting appendages must inevitably be facilitated by the “trussing” 
effect of wrapping, irrespective of the means of transportation. 
Once post immobilization wrapping at the capture site, type I, 
has evolved it may be exploited for a further function. Prey can then 
be safely left in situ and the process of removal from the web, and 
transportation, can be deferred until later. If the spider already 
has prey at the hub it may be advantageous to return from attacks 
as quickly as possible, and only cut out and carry further prey when 
it is ready to feed upon them. This process would split up a single 
sequence into two shorter sub-sequences. Nephila does not do this 
but transports all prey and stores them at the hub. All the Argiope 
species that we have studied store prey, in situ , in the web. (Storing 
prey in the web may increase the danger that they will be stolen by 
theridiid kleptoparasites. These are frequently found in association 
with the webs of Nephila clavipes and Argiope argentata in Panama. 
The very large size of Nephila webs may increase the spider’s diffi- 
culties in detecting the activities of the kleptoparasites and this could 
account for the fact that Nephila does not store prey in the web.) 
The step from post immobilization wrapping at the capture site 
to attack wrapping must confer adaptive advantages. It seems im- 
probable that these are related to the immediacy of escape prevention 
since the three species of Argiope described above, and Araneus 
diadematus , retain the immobilization bite for precisely those prey 
that have rapid escape potentials. (After Robinson, 1969, reported 
the use of the immobilization bite for non vibrating lepidopterans, as 
well as lepidopterans in general, we have found that this is true for 
several other, as yet undetermined, species of tropical araneids.) 
Where attack wrapping involves the prey being trapped under layers 
of silk thrown over it from a distance, it may enable spiders to attack 
prey with a diminished risk of injury to themselves. Certainly we 
have seen a Nephila lose a portion of its leg to the biting mouthparts 
