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wasp pounds the substrate by rapidly raising and lowering the head 
and body. The pressing and pounding behavior differ in the amount 
of time that the mandibles spend in contact with the substrate and in 
the height to which the wasp raises her head between substrate 
contacts. (3) The wasp assumes a nearly vertical position, applies the 
front of the head to the substrate and vibrates (high amplitude, high 
frequency) the entire head and body like a sort of pile driver. This 
behavior has been described explicitly only for A. procera (Wheeler 
and Wheeler, 1924; Evans, 1959). This behavior seems to differ from 
pressing by the angle of the body (although pressing with the body 
in a nearly vertical position can occur in any species depending on 
substrate conditions and whether she is in the burrow or not), the 
amplitude of the vibrations and the long, continuous time that the 
head is in contact with the substrate. Any of these packing move- 
ments may be accomplished with the mandibles alone or while hold- 
ing a stone, clump of soil, stick or piece of debris (i.e. tool use). 
(Some species combine these packing methods.) Most Sphecinae 
pick up a stone, clod of dirt, leaf, twig or other object, apply it to the 
substrate and push down while vibrating. This action serves either 
to embed the object or to pack the underlying soil or both. If the 
object is friable, the pressure and vibration serve to disintegrate it. 
Sometimes, and with some species more commonly than with 
others, wasps remove the object after having pressed it into the 
substrate and use it again or discard it to one side of the nest 
entrance (Table 1A; Peckham and Peckham, 1898; Rau and Rau, 
1918; Evans, 1959; Evans and West Eberhard, 1970). 
Tapping or pounding is a far less common form of packing behav- 
ior than pressing (Table 1 A). Repeated tapping of the substrate with 
the oral surface of the head has been observed in several species of 
trap-nesting and mud-daubing Sphecinae (Rau, 1937; Iwata, 1938; 
Tsuneki 1963b, 1968; Krombein, 1970; personal observation). While 
pounding some species of Ammophila hold a stone in the mandi- 
bles, thereby giving the appearance of using a hammer (Williston, 
1892; Peckham and Peckham, 1898; Rau and Rau, 1918; Wheeler 
and Wheeler, 1924; Evans, 1959, 1963, 1965; Powell, 1964; Evans 
and West Eberhard, 1970). The same stone is often used repeatedly 
and some authors describe the wasp as carefully selecting her 
hammer, picking up and discarding many stones before settling on 
one. 
