6 
Psyche 
[March 
and Gamboa areas of the Panama Canal Zone, 14 adult female 
Argiope argentata were found being consumed by Phiale adults. 
(On one count Phiale were found consuming 3 out of 64 spiders 
censused.) The spiders were, in all cases, off the web and resting 
on nearby vegetation. The araneid is considerably larger than 
the salticid (figure 3) and at least twice as heavy. A Phiale was 
also seen feeding on a late instar Nephila clavipes (F. Vollrath, 
pers comm.). No attacks were seen and it was not clear how the 
salticid had captured the araneid. To settle this problem, salti- 
cids were introduced into cages containing adult A. argentata (in 
webs) and watched. The web-builders were not fed and no attacks 
or “invasions” of the web were seen during intermittent observa- 
tions over a period of three days. Feeding one spider immediately 
gave a clue as to the attack method of the salticid. As the Argiope 
moved to attack a grasshopper the salticid became active and 
moved along the walls of the cage to various positions from which 
it clearly “looked” at the moving Argiope. No attack was made, 
but when the spider returned to the hub, leaving the wrapped 
prey at the capture site, the salticid moved to a position on the 
cage wall almost horizontally opposite the stored prey, and after 
a number of side to side movements of the cephalothorax, it leapt 
upon the prey to stand astride it, biting. The Argiope immediately 
started to make pumping movements at the hub (‘web-flexing’, 
Tolbert 1975). This movement shook the prey item and shortly 
after its commencement, the salticid jumped off and regained 
its former position on the cage wall. Feeding the same spider a 
second time resulted in a similar response on the part of the salti- 
cid. This time, after leaping on the completely motionless prey 
package, it did not provoke the Argiope into pumping, and fed 
undisturbed on the cricket for over five minutes. At this point 
the host ran to the stored prey and dragged it closer to the hub, 
and the salticid leapt off to regain the cage wall. The salticid made 
one more attack on the prey package and then 16J4 minutes after 
the start of the activity, attacked the spider at the hub by leaping 
on it. The Argiope was on the opposite side of the hub to the 
salticid and immediately dropped to the cage floor. The Phiale 
then walked on the web to the stored prey and fed upon it. Subse- 
quent experimentation showed that the salticids could regularly 
be induced to attack Argiope if the latter were provoked into 
moving. Attacks on the wrong side of the hub were not successful 
