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[Vol. 92 
incorporating alates from many colonies, with females later dispers- 
ing to form haplometrotic nests (Chapman 1957; Nagel and Ret- 
tenmeyer 1973; Holldobler 1976a, b; Davidson 1982). Veromessor 
pergandei , however, seems to produce many local, small mating 
aggregations, both temporally and spatially apart, where females 
fail to disperse after mating but actively form pleometrotic nests. 
Such differences may provide insight into the distribution and 
abundance of V. pergandei relative to Pogonomyrmex spp. 
Summary 
Veromessor pergandei , a seed-harvester ant common to the 
Mohave and portions of the Sonoran Desert, has a mating season 
lasting almost 2 months. Colonies release small numbers of alates 
on warm, cloudless and windless days from January to March in 
Phoenix, AZ. Release of alates from one colony often occurs with- 
out similar releases from nearby colonies. Dealate queens captured 
throughout the mating season are, nonetheless, usually inseminated. 
Veromessor pergandei usually initiates colonies through pleometro- 
sis; 89% of all queens collected in 1983 were pleometrotic. Several 
lines of evidence suggest males and females do not differentially 
disperse after mating; this failure to disperse from the mating aggre- 
gation may help induce pleometrosis in this species. Colonies of V. 
pergandei produce 9.7 times more mg of female alates than male 
alates on average. Length and timing of mating season and initial 
colony structure of V. pergandei differ dramatically from that of 
ecologically similar and sympatric Pogonomyrmex spp.; such dif- 
ferences may provide insight into the distribution of this species 
relative to Pogonomyrmex spp. 
Acknowledgements 
The Desert Botanical Garden and its personnel granted permis- 
sion to use their undeveloped habitat and provided enthusiastic 
support. J. C. Baldwin assisted in field surveys; ant dissections were 
performed by P. F. Ankney. B. Holldobler provided useful com- 
ments on an earlier draft. This work has been supported by an 
Arizona State University Faculty Grant-in-aid and National Science 
Foundation Grant DEB-8207052 (SWR, principal investigator). 
