1979] Chadab — Warning Cues for Social Wasps 119 
Table 1. Response of Prolopolybia exigua to visual tests of army ants in vials. 
Test 
Group 
Alert 
No 
Fanning 
Response 
moving ant 
14 
1 
0 
dead ant 
1 
5 
5 
moving ant concealed 
0 
1 
12 
end of a strip of paper 1 X 7 cm which was then held 1 cm from a 
nest for 2 minutes. Clean forceps and paper strips with 10 p\ of 
solvent were similarly tested as controls. For comparison six other 
ant species were tested, either crushed or extracted, and 3 chemicals 
known to be components of ant pheromones were tested by apply¬ 
ing 0.5 p\ to a strip of paper and tested as for the ant extracts. Tests 
of clean forceps and untreated paper strips were controls for those 
tests. Tests were conducted at a total of 53 nests of P. exigua, and 
the number and order of tests varied at each nest (Table 2). 
The wasps were tested for a response to 2 other army ants, Noma- 
myrmex esenbecki and Neivamyrmex pilosus in addition to Eciton 
burchelli and E. hamatum. Army ants of the former two genera 
have odors distinct from those of Eciton (Rettenmeyer 1963: 295), 
and though Nomamyrmex is known to raid wasps, such raids are 
probably rare (Chadab 1979). Non-army-ant species used in these 
tests were Azteca sp. and Monads bispinosa (Dolichoderinae), 
Camponotus sericeiventris (Formicinae), Ectatomma tuberculatum 
and Paraponera clavata (Ponerinae), all of which are common ter¬ 
restrial and aboreal scavengers and predators on other insects, but 
are not known to prey upon wasps. 
Chemicals tested were 1) citral, an alarm substance which has 
been identified from the mandibular glands of 2 ant species in 2 
subfamilies (Formicinae, Myrmicinae); 2) formic acid, which occurs 
in all members of the subfamily formicinae and is sprayed as an 
offensive-defensive chemical; and 3) 4-methyl-3-heptanone, which 
appears to be the most widespread alarm pheromone. . .in the 
Formicidae” occurring in members of 4 ant subfamiies (Ecitoninae, 
Myrmicinae, Ponerinae, Pseudomyrmicinae) (Blum 1973 and refer¬ 
ences contained therein). 
The wasps were commonly alerted by the test object, walking on 
the nest, raising their antennae, and orienting toward the object. 
Those activities demonstrated an awareness of the test object, but 
tests were considered positive only if at least 3 wasps participated in 
