1960] 
Evans — Bembix u-scripta 
49 
the season. Only a few females with badly worn wings and mandibles 
were still active, and even these ceased activity after June 25 (Evans 
1957). I returned to the area May 8-1 1, 1958, and found the wasps 
at the peak of their activity. C. S. Lin revisited the area June 3-7 of 
the same year and found that the males had disappeared and that nest- 
ing of the females was more advanced. Thus in this area the wasps 
first become active in early May (probably in late April) and the 
females remain active for six to eight weeks. The species is certainly 
univoltine, as cocoons collected June 23, 1956, gave rise to adult 
males and females in late March, 1957 (they were overwintered at 
room temperature at Ithaca, N. Y.). 
The colony was located on the protected beach of Laguna Madre 
about five miles west of Port Isabel. The soil here is a rather heavy, 
dark sand containing pieces of shells and bits of organic matter (chiefly 
bits of decayed seaweed and beach halophytes). This beach is occasion- 
ally swept by waves from Laguna Madre (which is salt), especially 
during the fall and winter, but there is little tide action. On certain 
parts of the beach there are extensive patches of low vegetation, chiefly 
Salicornia , certain composites, and various grasses. The wasps oc- 
curred only in bare places on the middle of the beach, that is, from 
about 8 to 15 meters above the high water mark hut below the banks 
at the upper edge of the beach. 
Behavior of males. — Males were observed only during early May, 
1958, but at that time they were very abundant. Each morning we 
entered the area about 0800, and at this time the males were already 
engaged in their “sun dance”. Each male flew rapidly in loops, figure 
eights, and irregular patterns only 2-6 cm. above the sand surface, 
much as in Bembix cinerea (Evans 1957). By 1030 some reduction 
of males could be noted, and by 1115 each day the last male had dis- 
appeared. By 1500 a few males were once again active, and from 
1600-1900 each day there was a second though somewhat less popu- 
lous sun dance. The greater part of this sun dance occurred in a 
small area somewhat apart from the major nesting area of the females, 
although males often flew briefly over various parts of the beach before 
rejoining the sun dance. 
During the middle of the day, and also at night, the males enter 
short, oblique burrows in the sand and throw up a small barrier of 
sand behind them. These burrows tend to be grouped in small clus- 
ters. They are dug by the males, but the males usually re-enter an old 
burrow rather than digging a new one each day. 
