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[Vol. 92 
flying from the nest during a 2 min. period. Observations continued 
until above ground activity ceased or reduced to only “nest work” 
with no further sighting of alates. Fewer than 10 alates flying from a 
nest per min. was regarded as “low intensity” flight activity while 
^ 10 alates per min. was regarded as “high intensity” flight activity. 
We observed colony foundation at several sites in South Moun- 
tain Park, Phoenix, Arizona. The habitat at South Mountain is 
similar to that at the Botanical Garden (the two areas are 17 km 
apart) but includes several sandy ravines not found at the latter. 
These ravines attract founding queens which are easily collected or 
excavated. In 1983 we made as complete a sample as possible of all 
founding nests along one of the ravines at South Mountain. This 
survey occurred late in the flight season (in mid-March) when most 
females were expected to have flown and established nests. 
A similar survey of founding nests was conducted in a second 
ravine in 1984 to chart the course of colony foundation throughout 
the flight season. Approximately every other day (and every day 
that flight activity was observed at the Botanical Garden) the ravine 
was surveyed and all founding nests collected. Care was taken to 
examine apparently preferred nest establishment sites, e.g. under 
flat rocks, boards and other such objects. Sixty-one of the queens 
collected during these 1984 surveys were dissected to determine mat- 
ing success throughout the flight season. 
During the first half of the 1984 mating season we also partially 
excavated adult V. pergandei nests and collected all alates found. 
Samples were counted according to sex, dried and weighed 
individually. 
Results 
Mating season of V. pergandei was almost 2 months long (Fig. 1). 
While there was some coordination of flight activity between nests 
(e.g. 7 March, Fig. 1), on numerous days only one colony released 
alates, e.g. nest Vp-1 (lowest histogram in Fig. 1) released alates on 
1 1 days when no other observed nest did so. Most of the days during 
which no flight activity occurred appeared too cold, overcast or 
windy for flights. As a proximal cue, even light wind appeared 
sufficient to preclude flight. We frequently observed alates gather at 
the nest entrance and then run into the nest in apparent response to 
breezes or stronger gusts. 
