IO 
Psyche 
[March 
provisioning would seem uneconomical unless the wasp is able to 
maintain two or more nests simultaneously. However, two progressive 
provisioned which maintain only one nest at a time nested in some 
abundance in the same area; these were Bembix spinolae and Steniolia 
obliqua. The only other species of Ammophila found here was a 
single female A. macra Cresson which nested on the edge of the bare 
soil on August 14; I have presented a few notes on this wasp below, 
as it presented a striking contrast to azteca. 
In Jackson Hole, A. azteca appeared to be strictly confined to 
patches of bare, moderately firm, sandy loam along the river; none 
were seen or taken in general collecting in other habitats. The major 
nesting area was about 20 meters long and varied from 5 to 8 meters 
in width, paralleling the river and separated from it only by a narrow, 
oblique bank which was not used for nesting. Parts of this area were 
covered with grass and herbs, chiefly around several trees, but these 
places were not utilized by the Ammophila. Also, the Ammophila 
did not nest in a small plot of very loose sand which was occupied by 
a colony of Bembix spinolae. The area was surrounded on the three 
sides away from the river by open woodland in which the dominant 
tree was lodgepole pine (Pinus contorta latifolia) ; near the river 
there were also narrow-leaved cottonwoods (Populus angustifolia) 
and willows ( Salix spp.). I estimated that there were about 50 
females scattered about the nesting area. My notes cover 20 females, 
but only a few of these were marked, and only four of the marked 
individuals were followed over a period of days. The most complete 
observations pertain to no. 2030, which was marked with a red spot 
on the second day of study ( July 19) and followed until August first, 
including one complete day of observation (July 31) and observations 
for several hours on five other days. 
That it was impossible to make continuous records of more than a 
very few females was a consequence of the fact that females spaced 
themselves widely, each maintaining a small nesting arena, no more 
than 30 cm. in diameter, where all her nests were prepared (Figs. 6, 
7). These arenas were separated, for the most part, by half a meter 
or more. On one occasion an unmarked female shared a circumscribed 
area with a marked female (no. 2028C), the nests of the two being 
more or less intermingled, but this was exceptional. I observed no 
aggression among females provisioning their nests, but females digging 
in proximity would sometimes attack one another. It seems possible 
that there is a measure of territoriality among females of this species, 
but since the wasps spend only a small portion of their time in the 
nesting arenas, contacts between neighboring females are few. 
