1979] Matthews, Hook & Krispyn — Behavior of Crabro 151 
Crabro hilaris F. Smith 
This previously unstudied species was discovered on October 
29-30, 1977 when several nests were found at two inland localities. 
A check of the same localities on October 5, 1978 failed to turn up 
any C. hilaris, which suggests that this species is a late season nester. 
Intensive collecting on the island throughout the summers of 1977 
and 1978 and the early spring of 1978 also failed to turn up any 
specimens suggesting that the species is univoltine. 
The majority of our observations were made along a plowed strip 
of sandy loam soil extending across a grassy clearing of about 100 
m. The habitat (Fig. 2) had been created earlier in 1977 (late July) as 
a firebreak approximately 1 m wide. We counted about 30 active 
nests along this firebreak. Another smaller aggregation of about 15 
nests was found in sandy soil adjacent to a road several km away. 
Eight nests were successfully excavated. These contained from 
1-5 cells per nest. Burrows descended nearly vertically (Fig. 3); cells 
were situated 5-8 cm to the side of the main burrow and averaged 28 
cm deep (ranges 25-38 cm; n= 14). Two measured cells were 7.5 X 14 
mm and 6 X 20 mm. Cells contained an average of 9 flies (range 
4-14; n=13). Prey were identified as follows: 
Sciomyzidae: 
Syrphidae: 
Muscidae: 
Calliphoridae: 
Sarcophagidae: 
Tachinidae: 
Dictya sp. -1 
Allograpta obliqua (Say) - 4 
Toxomerus geminatus (Say) - 1 
Coenosia sp. - 6 
Cochliomyia macellaria (F.) - 1 
Camptops unicolor Aldrich - 3 
Sarcophaga sp. - 1 
Ceracia dentata (Coquillett) - 1 
Spathimeigenia spinigera (Coq.) - 1 
One female was observed to initiate a new nest only 1 cm away 
from her previous nest. Soil was loosened with the mandibles and 
forelegs and pushed backwards with the assistance of the mid and 
sometimes the hind legs. As she digs the female slowly rotates 
through 360° while penetrating the surface and she was very soon 
completely hidden by the accumulating mound. Nest entrances were 
surrounded by a conspicuous tumulus of unleveled soil averaging 
about 5 cm diam. Burrow diameter was 4-5 mm. 
