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[Vol. 87 
Psyt 
more time guarding her nest (Evans 1966). In addition, Malyshev 
(1968) suggested that prey items are fresher and less likely to be 
unsuitable to offspring when supplied progressively. 
The genus Ammophila is interesting because it encompasses the 
evolutionary transition from oviposition upon a single prey to 
progressive provisioning (Evans 1959, Powell 1964). Studies of 
representative species can clarify the successive steps in the evolution 
of a more complex behavior, i.e., progressive provisioning, from its 
simpler antecedents. Here we report on the method of provisioning 
followed by Ammophila aberti Haldeman, a species suspected of 
practicing delayed or progressive provisioning (Hicks 1932, Evans 
1959, Powell 1964). In addition, we provide data on prey records, egg 
placement, and report observations that suggest facultative clepto- 
parasitism. 
Study Site and Methods 
A small nesting population of A. aberti (12 females) was observed 
at Greenville Farm (GF), an agricultural experiment station operated 
by Utah State University in North Logan, Cache County, Utah. In 
contrast to a report by Hicks (1932) that A. aberti is bivoltine at 
Boulder, Colorado, this species is univoltine in northern Utah and 
flies from the first half of July to late August. Our observations were 
made on three consecutive days beginning 23 July and then 
sporadically through 4 August. 
The wasps nested in three bare, moist 6m 2 soil beds that were 
prepared and maintained for a population of alkali bees ( Nomia 
melanderi Cockerell; Bohart 1972). The beds were surrounded by 
experimental plantings of alfalfa, sugarbeets, wheat, and vegetable 
crops. Wasps were marked with acrylic paints on various parts of the 
body, and their nests were marked with similarly painted toothpicks. 
We also applied dots of paint to the plugs of closed nests to determine 
if nests were visited during our absence. 
Nests at GF could not be excavated without disturbing both the 
wasps and alkali bees that used the beds. Instead, we excavated nests 
of A. aberti from a large population that nested in a 1 ha alkali flat at 
Cornish, Utah, 40 km northwest of GF. Soil at Cornish was mostly 
bare with some patches of pickleweed ( Allenrolfea occidentalis (S. 
Wats.) Kuntze) and moist because of seepage from a nearby 
irrigation ditch. An alfafa field b&rdered the nesting site on one side 
and halophytic shrubs (e.g., Sarcobatus, Cercocarpus, Atriplex) on 
