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[Vol. 87 
of delayed provisioning. Any of several possibilities might explain 
this relatively high incidence of “delayed” provisioning. The first is 
that the population is behaviorally polymorphic for the provisioning 
trait(s), i.e., that both mass and delayed provisioning behaviors 
currently exist. A second possible explanation is inter-individual 
variability in the speed with which prey can be found, subdued, and 
returned to the nest. Nests that appear to have been provisioned on a 
delayed basis may simply be the work of individuals that are less 
efficient at hunting than others. Our data are not detailed enough to 
allow additional discussion of these possibilities. 
A third (and more likely) explanation is that A. aberti is a mass 
provisioning species but that the rate of provisioning is influenced by 
environmental circumstance. As Evans (1966) points out, the dis¬ 
tinction between mass and delayed provisioning is a tenuous one. 
Indeed, if provisioning is delayed merely because of inclement 
weather (as were two nests at GF) or temporary paucity of prey as 
Evans (1966) suggests, then any distinction between mass and 
delayed provisioning is artificial. Proof of delayed provisioning 
requires that the insect delay its pace of provisioning even when prey 
are abundant and weather conducive to flight, and A. aberti does not 
appear to do this in any consistent way. Hicks (1932) also reported 
that nests were sometimes completed rapidly and at other times 
slowly but offered no explanation for these differences. 
It is not clear why females abandon so many nests. Brockmann & 
Dawkins (1979) found that many of the nests abandoned by the 
female Sphex ichneumoneus were later used by other females, and 
they concluded that if abandonment was due to unsatisfactory 
substrate or nest location, these conditions must have been tem¬ 
porary. In the small population we studied, abandoned nests were not 
re-used later. Tsuneki (1963) and Evans (1966) have suggested that 
the “false” burrows constructed adjacent to the main nest entrance by 
several digger wasp species may serve to decoy parasites. Con¬ 
ceivably, abandoned nests could serve the same purpose but as 
Brockmann and Dawkins (1979) have pointed out, decoys would 
have to benefit the females that dug them more than other unrelated 
members of the population. This might be the case if females tended 
to cluster their nests within a relatively restricted area. Then enemies 
that invaded abandoned unrewarding nests might be discouraged 
from additional searching in the immediate area (Tepedino et al. 
