1988] Deyrup, Cronin, & Kurczewski — Alio chares 267 
before we introduced the wasps. Vertical cardboard strips, 4 cm 
wide, were placed in each of four corners of the cages, extending 
from top to bottom of the cages. The placement of the strips pro- 
duced artificial crevices about 1 cm deep between the cardboard and 
the screening. Most of the spiders spun webs with retreats between 
the screening and the cardboard, so the behavior of the spider and 
the hunting wasp could be observed easily. Additional spiders were 
introduced into cages to replace those taken by the wasps, and these 
spiders readily occupied vacated webs. Spiders were provided var- 
ious insect prey, chiefly tabanids. Five female A. azureus were col- 
lected as they hunted F. hibernalis around buildings and introduced 
singly into the cages. Additional wasps were reared in the labora- 
tory. We observed more than 50 hunting sequences, both in the 
field and in the laboratory. Once parasitized, most spiders were 
removed from their cages and placed in vials, although a few were 
left in the cages. Male wasps were collected outdoors as they were 
attracted to cages containing virgin females. When wasps emerged 
from their cocoons in the laboratory, they were usually placed in a 
cage with a member of the opposite sex. Females were later admit- 
ted into cages containing spiders. Spiders and wasps were kept at 
24° C. A honey-water solution was provided ad libitum as nourish- 
ment for the caged wasps. 
Hunting Behavior 
F. hibernalis builds its web (Fig. 2A) in cracks and recesses in 
sheltered sites, and it is in such places that we observed A. azureus 
hunting outdoors. Because A. azureus normally attacks spiders in 
dark, restricted places, the confines of our laboratory setup did not 
appear to impose too unnatural a situation on the hunting wasp. 
Wasp behavior in the laboratory appeared very similar to the behav- 
ior observed in the field. A. azureus hunts primarily on foot, run- 
ning rapidly with the short rushes and wing-flicking typical of many 
pompilids. Occasional flights of a meter or less are made to new 
hunting spots. The wasps were sometimes tolerant of human 
approach, and occasionally continued hunting when we approached 
for close observation. Any attempt to capture a wasp was likely to 
cause it to fly out of sight. 
When a wasp encounters a Filistata web, she pauses, orients 
toward the center of the web, and quickly walks into the central 
