1985] 
Moffett — Behavioral notes on Acanthomyrmex 
173 
During these nest shifts a consistent route often developed 
between the old site and the new. The emigrating ants observed in 
the field also followed a distinct route, which in this case could have 
been at most a few centimeters wide. 
Defensive Behavior 
Acanthomyrmex notabilis. Foraging minor workers of both 
Acanthomyrmex species were very shy, retreating even after slight 
disturbances. However, when workers of Pheidologeton, Aphae- 
nogaster, and Pristomyrmex species common in the vicinity of the 
nest of A. notabilis were held in forceps up to the nest entrance, 
minors soon emerged to bite at the forager and sometimes grapple 
with it; the Pristomyrmex evoked the strongest response. Following 
such an experiment, no ants emerged to forage for at least five 
minutes. After withdrawing each “intruder,” I could barely make 
out the head of a major worker just within the entrance, where no 
major had been previously. The major bit at a forceps tip that I 
pushed inside the entrance, holding on so tenaciously I could pull it 
from the nest. 
Captive workers could likewise be provoked to seize a forceps tip, 
particularly when the worker was in or near the brood area. Biting 
ants commonly held on so tenaciously that they could be pulled free 
from the ground. When pulled free, they usually released their grip 
within a few seconds, unless their tarsi still clung to a piece of 
substrate, such as a bit of soil — in which case majors in particular 
would maintain a grip for as long as a minute (fig. 3). Minors 
gripping a loose object usually rotated that object forward beneath 
them, while majors did not. Possibly this is explained by a tendency 
for minor workers to pull backwards when grappling with an 
intruder. 
Captive A. notabilis workers fled from Solenopsis and Monomo- 
rium ants, and there was a rapid exodus of the ants and brood if an 
intruder entered the nest area. However, if the intruders first had 
their gasters excised, the A. notabilis ants behaved much as they 
did towards single Pheidologeton diversus minor workers, which 
lack the severe stings of Solenopsis and Monomorium. In this case an 
A. notabilis minor often stood its ground for several seconds, either 
repeatedly biting at the intruder, or swinging its gaster under its 
body towards the intruder, or both. A major most commonly first 
