50 
Psyche 
[September 
During the sun dance the males fly, at least some of the time, with 
their middle and hind legs hanging down. When they approach a fe- 
male they attempt to descend upon her from above and grasp her with 
the legs. During this time the pair rise a meter or two in the air, then, 
if the female is receptive, descend to the ground, where copulation 
occurs. During mating, the male rests on top of the female, often 
buzzing his wings (perhaps to maintain balance), while the female re- 
mains completely motionless, her wings being clamped in place 
by the middle legs of the male. The spines of the middle femora of 
the male apparently fit over the wing-bases of the female, while the 
arcuate middle tarsi of the male appear to fit over the coxae of the 
female. The front legs of the male extend rigidly forward and the 
hind legs rigidly backward during copulation ; neither pair is in con- 
tact with the female or the substrate. The male genitalia are of 
course extruded and work up and down rhythmically until they gain 
entry into the genital chamber of the female. The longest copulation 
observed lasted two minutes. 
Nesting behavior of females. — Most of the females were concen- 
trated in one large bare area on the beach. In this area there were at 
least 100 nests, many of them only a few centimeters apart. Nests on 
the periphery of the colony tended to be more widely separated. Here 
and there along the beach there were other smaller groups of nests, 
so that the total may have approximated 200. 
Most new nests appear to be started in the morning (0900-1030). 
The female is able to dig about 10 cm. an hour, but because of fre- 
quent periods of inactivity, especially at midday, the greater part of 
a day is generally required to complete a nest. Much use is made of 
the mandibles in loosening the soil, and this results in much wear of 
the mandibles as the season progresses. The soil which is loosened is 
scraped back with the front legs in the usual manner of wasps of this 
genus. When the burrow is a few centimeters deep, the wasp allows 
the soil to clog the entrance, sometimes for long periods, before finally 
coming out and scraping it back from the entrance. The digging 
movements appear rather slow as compared to other species of the 
genus. 
As digging progresses, a large mound of sand accumulates behind 
the entrance. This mound measures, on the average, about 18 cm. 
long, 10 cm. wide, and 1.5 cm. high. When the nest is completed, 
some individuals level this mound. The leveling movements aie very 
characteristic and unlike those of any other known Bembix. The fe- 
