Psyche 
[June-September 
resting position. Contact between the gaster and carton during the 
buzzing vibrated the envelope and nest leaf probably communicat¬ 
ing alarm to other wasps (West-Eberhard 1969: 16, Naumann 1970: 
120). Naumann (1970) described a similar behavior for Protopoly- 
bia acutiscutis (=pumila), but it has not been reported for other 
polistine genera. 
Group fanning continued until the first three or four army ants 
ran onto the nest. At that point the wasps flew from the nest in 
unison. In one raid observed, army ants ran back and forth for 10 
minutes on the leaf supporting a wasp nest before making actual 
contact with the wasps; the wasps exhibited group fanning during 
the entire period. 
Clearly, the wasps did not use physical contact to detect the army 
ants; the form, movement, or odor of the army ants probably 
alarmed the wasps. The efficacy of a visual cue in eliciting alarm 
from the wasps was tested by placing a single army ant in a clear, 
sealed vial and holding it in 30-cm forceps 1 cm from a P. exigua 
nest. Tests were conducted only when there was a minimum of three 
wasps on the nest surface. As a control the same vial (ant inside) was 
covered with opaque tape and was tested similarly. During the tests 
the army ants typically ran back and forth in the vial. A third test 
was therefore done to investigate the effect of movement of the ant: 
a dead ant was placed in a clear, sealed vial and tested. 
The responses of the wasps were scored in 3 categories: alarm 
(group fanning), “alert”, and no response (Table 1). The moving ant 
consistently elicited alarm, the dead ant alert, and the control vial 
no response. These results demonstrate that the movement of the 
army ant is an important component of the alarm cue. However, 
numerous other observations on P. exigua showed that the wasps’ 
response to a moving army ant was not specific but a generalized 
alarm response to small moving objects. Phorid flies, spiders and 
various non-army-ant species elicited alarm when wasps saw them 
or their shadows through the leaf to which the nest was attached. 
Tips of forceps elicited alarm when moved rapidly back and forth 
above a nest leaf but not when held motionless. 
To test whether odors of army ants might also elicit alarm from 
the wasps two procedures were used: 1) single army ants were 
crushed in forceps, concealed between the tips and held 1 cm from a 
nest for 2 min, or 2) 10 whole army ants were extracted in 1 ml of 
solvent (methylene chloride) and 10 p\ of the extract applied to the 
