1960] 
Evans — Bembix u-scripta 
5i 
male (without closing the nest entrance) backs out to the middle of 
the mound of sand, then walks forward in a straight line scraping 
sand backward. When she arrives at the nest entrance, she turns to 
one side at a 45-90° angle and continues for another 1-3 centimeters, 
still scraping sand, which now falls over or slightly beyond the nest 
entrance. She then flies back to the center of the mound and repeats 
Fig. 1 — Diagram of leveling movements of Bembix u-scripta. In a is 
shown the completed mound of earth with the open (blackened) nest en- 
trance at one end. In b three typical routes of a female leveling the mound 
are shown; dashed lines indicate movement by flight. In c is shown the 
final product, with the nest entrance covered (indicated by dashed line) and 
mound well removed from entrance. 
the performance. After a time this results in the soil immediately in 
front of and around the nest entrance being well scattered and flat- 
tened. However, the extremity of the mound of soil has not been 
touched and has in fact been added to. Thus the net result of the 
leveling movements is to move the bulk of the accumulated soil from 
the nest entrance to a position well removed from it (by about 8-12 
cm.) (fig. 1). 
In this colony relatively few individuals leveled the mound. We 
estimated that about 25% leveled, while some others exhibited weak 
and indefinite leveling movements. The remaining members of the 
colony left the mound of earth completely intact. As additional cells 
are added to the nests, some additional soil is added to the mound; 
