408 
Psyche 
[December 
This note describes the web and predatory behavior of another 
species of the Ariamnes group, Argyrodes attenuatus, which attacks 
ballooning immature and mature male spiders, and also minute 
“trapeze” flies which use its web as a resting place. This spider’s web 
serves not as a trap, but rather as a resting site for both types of 
prey, and as a substrate for the spider’s stealthy attacks. 
Observations 
Argyrodes attenuatus is widely distributed in Central and South 
America (Exline and Levi 1962). The observations reported here 
were made on Hacienda Mozambique about 15 km SW of Puerto 
Lopez, Meta, Colombia (el. approx. 200 m) between June and 
August 1978 in two patches of periodically flooded forest from 
which some trees had been cut. The forest at one site was in at least 
an advanced secondary stage with some relatively large trees, while 
the other was younger. Voucher specimens have been placed in the 
Museum of Comparative Zoology, Cambridge, Mass. 
Resting Position and Web 
More than 40 spiders were seen from 1-3 m above the ground, 
resting on sparse, irregular, three-dimensional networks of long 
threads (Pig. 1). The networks ranged from two or three up to seven 
threads, some of which reached lengths of up to 1-2 m; careful 
inspection showed that none of the threads were sticky. 
During the day the spiders usually rested with all their legs 
pressed tightly together, with I and II directed forward and III and 
IV backward, and the abdomen straight or nearly so, giving the 
animal a stick-like appearance. At night the legs, especially the front 
ones, were often spread. The spider always rested at a junction of 
two or more threads. Although the spider could control the form of 
its long thin abdomen, and sometimes curled it into a tight spiral, I 
never saw an individual move it in an undulatory or inchworm-like 
fashion as Goldi (in Exline and Levi 1962) saw A. (A.) longissimus 
do ( I did not disturb the spiders as Goldi apparently did, however). 
The adaptive significance of the extraordinary abdomen of A. 
attenuatus may be at least partly outline camouflage rather than 
imitation of inch worms as proposed by Exline and Levi (1962). 
