1979] Matthews, Hook & Krispyn — Behavior of Crabro 153 
Nest entrances are left open during periods of active provisioning 
and closed at night. Prey-laden females typically approach from 
about 2/3 m above their entrance and then slowly descend nearly 
vertically into the open entrance. Flight is silent and prey is held 
venter up by the middle legs. Provisioning appeared to occur 
throughout the day. Departing females were often observed to rest 
motionless with their head blocking the nest entrance for several 
minutes before departure. 
Parasitism by miltogrammine flies was 26.7% overall with 
maggot-infested cells found in nests from both aggregations. As 
many as 6 maggots were found in a single cell. Those reared were 
identified as Senotainia sp. or S. trilineata (Wulp). 
Three adult wasps were successfully reared from cocoons main¬ 
tained at room temperature. A male emerged the following Febru¬ 
ary and a female emerged in mid-April, followed by another in May. 
Miller and Kurczewski (1976) have made observations on two 
other members of the hilaris species group. 
Crabro argusinus Packard 
This species was clearly bivoltine, having both a spring and a fall 
generation on St. Catherine’s Island. In late April, 1978 it was with¬ 
out question the “dominant” species of solitary wasp, occurring 
ubiquitously over the island. We studied it principally at 3 localities 
(Fig 1). One was at the northern end of the island where it nested in 
steep eroding sand cliffs and blowouts adjacent to the ocean (Fig. 4) 
that we termed the “north beach site”. Another was termed the 
Wamassee Creek site and was located on the western edge of the 
island. Here the wasps nested sparsely over a large area of sand 
bank exposed by the meandering Wamassee Creek. The third study 
site was called the “boiler site” because of its proximity to an aban¬ 
doned oyster boiler (Fig. 5). This locality was considerably more 
protected than the north beach area and the Wamassee Creek site 
was surounded on three sides by salt marsh. In contrast to the nearly 
vertical nesting surfaces at the other sites, nests at the boiler site 
were constructed in flat, more or less open sandy soil having a 
surface of crushed oyster shells. High tide level came to the edge of 
the nest area with the highest of the spring tides occasionally briefly 
inundating the entire nest site. The nesting population at the boiler 
site was rather localized, consisting of about 50 nests concentrated 
in an area of about 2 X 8 m. Nests at the north beach and Wamassee 
