STATARY BEHAVIOR IN NOMADIC COLONIES 
OF ARMY ANTS: 
THE EFFECT OF OVERFEEDING 
By Howard Topoff, Aron Rothstein*, Susan Pujdak, and 
Tina Dahlstrom** 
Department of Psychology, Hunter College of CUNY, New York, 
N.Y. 10021, and The American Museum of Natural History 
Introduction 
Nearctic colonies of the army ant Neivamyrmex nigrescens 
Cresson (subfamily Ecitoninae) exhibit behavioral cycles consisting 
of alternating nomadic and statary phases. During the statary 
phase, a colony remains at the same nesting site and forages 
irregularly for food. The nomadic phase, by contrast, is character- 
ized by night-long raids and frequent emigrations to new bivouacs. 
According to Schneirla (1957, 1958), the nomadic phase is triggered 
by stimulation arising from newly-eclosed callows, and is subse- 
quently maintained by comparable excitation from the developing 
larvae. Experimental support for brood-stimulation theory stems 
from studies showing: (1) an abrupt reduction in nomadism after 
removing a portion of a larval brood (Schneirla and Brown, 1950); 
and (2) the eclosion of a pupal brood (in the absence of newly- 
hatched larvae) is indeed sufficient to initiate a nomadic phase 
(Topoff et al., 1980a). Recent studies have suggested, however, that 
brood stimulation may in turn depend on the degree of brood 
satiation. Thus, in a preliminary field study involving food aug- 
mentation, Mirenda et al. (in press) was able to halt the occurrence 
of emigrations during a portion of the nomadic phase in colonies of 
N. nigrescens. This was followed by more prolonged laboratory 
studies (Topoff and Mirenda, 1980 a,b) showing that the frequency 
and direction of nomadic emigrations are indeed influenced by the 
amount and location of food. 
This paper reports findings from our continued studies of food 
augmentation for colonies of N. nigrescens. In previous studies, 
larval stimulation was reduced by artificially feeding colonies early 
in the nomadic phase, after callow eclosion. Because an additional 
*Department of Biology, City College of CUNY, New York, N.Y. 10031 
**Department of Zoology, University of California, Riverside, CA 92521 
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