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Psyche 
[Vol. 92 
Downes. This provided us with the opportunity to examine: (1) the 
effects of cleptoparasitism on the reproductive success of a progres- 
sive provisioner; (2) the behavioral strategies of the flies in attempt- 
ing to parasitize A. harti nests; (3) the actual means by which 
cleptoparasitism is reduced; and, (4) the behavioral responses of A. 
harti to the presence of the flies. 
Study Site and Methods 
The study was conducted near Auburn, Cayuga County, NY, 
between 2 June-29 Aug 1982 and 21 June-22 Aug 1983. A descrip- 
tion of the site is given elsewhere (Hager and Kurczewski, 1985, 
1986). The behavior of P. aurifacies and S. vigilans was recorded in 
order to obtain average hourly, daily and seasonal activity rates. 
These rates are reported in mean number observed behaviors/ sam- 
ple hr to account for differences in sampling effort. The data for the 
two years are pooled. To provide greater biological significance, 
calendar date is adjusted to reproductive date with reproductive 
date 1 corresponding to the first day of A. harti nesting activity. 
Figure 1. Weekly activity (mean no. observed behaviors/ sample hr) of Senotai- 
nia vigilans and Phrosinella aurifacies in Ammophila harti nesting aggregation, 
combined for 1982 and 1983. Week 1 corresponds to first week of A. harti nesting. 
