MATING SEASON AND COLONY FOUNDATION 
OF THE SEED-HARVESTER ANT, 
VEROMESSOR PERGANDEI 
By Gregory B. Pollock 1 * 2 and Steven W. Rissing 1 * 3 
The seed harvester ant Veromessor pergandei is common in most 
of the Mohave Desert and xeric portions of the Sonoran Desert of 
the United States and Mexico (Creighton 1950). Throughout exten- 
sive portions of its range it is sympatric with ecologically similar 
Pogonomyrmex spp. (Cole 1968, Wheeler and Wheeler 1973, 
Davidson 1977a, Rissing 1981). Hypotheses to explain coexistence 
of these species include use of different foraging temperatures 
(Bernstein 1974), foraging methods (Davidson 1977b), preferred 
forage item size (Davidson 1977a), and method of predator avoid- 
ance (Rissing 1981). While information is available regarding 
reproductive behavior and colony structure of Pogonomyrmex spp. 
(Holldobler 1976a, Markl et al. 1977, MacKay 1981, Davidson 
1982), comparison with V. pergandei is precluded by lack of infor- 
mation for the latter. Accordingly, we have observed mating season 
and colony foundation of V. pergandei. 
Materials and Methods 
Previous observations of V. pergandei in central Arizona indi- 
cated mating flights occur in late Winter/ early Spring at midmorn- 
ing, under clear skies as air temperatures reach approximately 22° C. 
Five V. pergandei colonies on an undeveloped section of the desert 
Botanical Garden, Phoenix, Arizona, were selected for observation 
of flight activity during this period. The 10 ha study area is native 
Sonoran Desert with Larrea tridentata, Carnegia gigantea and Pro- 
sopis velutina predominant woody plants. All nests were observed 
daily from 28 January to 20 March 1984 unless it was overcast, 
during which time all nests were completely inactive. Each morning 
an observer visited each nest and counted total number of alates 
'As equal contributors. 
2 School of Social Science, University of California, Irvine, California 92717 
'Department of Zoology, Arizona State University, Tempe, Arizona, 85287 
Manuscript received by the editor October 25, 1984 
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