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Brockmann — Digger wasps 
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pavement, or by pushing stones, sticks, leaves or other debris into 
the nest entrance (Table IB). Finally, the wasps disguise the location 
of the nest by scraping soil in the vicinity and by moving leaves, 
sticks and other debris in the area over or near the nest entrance 
(Fig. 4; Table 1A). Some wasps do not perform this disguising 
behavior at all, whereas others move a few objects around in a 
perfunctory manner and still others spend long periods of time care- 
fully concealing the nest entrance (Evans, 1959; Peckham and Peck- 
ham, 1898). Like other aspects of nesting behavior, nest-closure is 
highly variable, with individuals sometimes spending long periods 
of time filling, whereas at other times they only partially fill the 
burrow or do little packing (Adriaanse 1943; Tsuneki, 1968; Ristich, 
1953; Hartman, 1905; personal observation). 
The Sphecinae that dig the nest before hunting usually have some 
sort of temporary nest closure while they are away from the nest. 
Ammophila usually cover the nest at the surface with a pebble or 
piece of debris selected to fit the burrow entrance precisely (Evans, 
1959, 1965). Sphex scrapes and nudges a little soil across the 
entrance to the side-tunnel, but leaves the main-tunnel open while 
they are out hunting. At the end of the day, most Sphex close off the 
nest overnight, digging it out again in the morning. This temporary 
overnight closure differs from the final closure in that the wasp 
quickly scrapes loose soil into the burrow, turning around to pack 
only occasionally and for shorter periods of time. In contrast with 
this, during the final nest closure, the wasp alternates a few scrapes 
of soil into the nest followed by long bouts of intensive packing (Fig. 
3). The result is that the soil in the temporary closure is loose where- 
as in the permanent closing the soil is tightly compacted. When 
excavating even a recently closed nest, it is very difficult to distin- 
guish the soil of the closure from the surrounding soil. 
Packing Behavior 
There are three general methods of packing soil into the burrow 
which grade into one another. (1) The wasp applies the clypeus and 
open mandibles to the substrate and pushes or presses down on the 
soil, usually while making low amplitude, high frequency vibrations 
of the head and body (Fig. 3). The body is normally angled well 
below the vertical; the wasp may raise her head and then press down 
again repeatedly within a short period of time at the same or slightly 
different spot. This action seems to grade into pounding. (2) The 
