1969] 
Robinson — Predatory Behavior 
495 
Table 1. 
A comparison of times spent away from the hub of the web by Argiope 
argentata and Nephila clavipes with Trigona sp. as prey. 
A. Uninterrupted sequence (single Trigona ). Prey n = 50, 
Spider n = 10 of each sp. 
Mean total 
time. 
Nephila 70 secs. 
Argiope 77 secs. 
Range 
44-108 
38-192 
Standard 
deviation 
15 
40 
Standard error 
of mean 
2.1 
5.6 
B. Ten Trigona per spider, arriving at 30 second intervals (see text for 
explanation). Data from 50 successful sequences of attack by 10 
spiders of each species. 
Mean total 
time. 
Nephila 30 secs. 
Argiope 18.7 secs. 
Range 
14-65 
7-33 
Standard Standard error 
deviation of mean 
11.8 1.7 
7.8 1.1 
Times in A are for the total prey capture sequence: attack, removal from 
the web, transportation, storage at the hub. In B the times for Argiope are 
for attack, storage in the web and the spiders’ return to the hub (since 
the spider omitted removal of the prey from the web and its transportation). 
from the hub may be especially critical under conditions when prey 
arrive in rapid succession. Both Nephila clavipes and Argiope ar- 
gentata deal with stingless bees ( Trigona sp.) in predatory sequences 
of similar duration, see Table i. However, Argiope uses immobiliza- 
tion wrapping whereas Nephila does not wrap the bees until it 
reaches the hub. Agriope has the potential of being able to omit the 
immediate removal of the prey from the web ; and its transportation, 
whereas Nephila has not. We, therefore, decided to test the two 
spiders under conditions when several prey were arriving at the web 
in succession. To do this we allowed one bee to fly towards either a 
Nephila or an Argiope web every thirty seconds until ten prey had 
flown at the web. The Trigona were released from a glass tube held 
1 8 " from the web and 6" vertically below the spider. By having a 
light source behind the web we ensured that the bees would fly 
towards the web rather than in any other direction. The dispersion 
of the bees on hitting the web was approximately standardized by the 
constant position of the escape tube. Each of 20 well fed Nephila 
and 20 well fed Argiope (mature females in each case) were tested 
with one succession of io bees. We made notes of the fate of each 
insect and timed and noted the behavior of the spider. The results 
are shown in Figure i. This reveals a basic difference in the prey 
