32 
Some Solitary Wasps of Texas. 
times many trips are made before the caterpillar is taken inside and 
it is usually a tight fit and requires considerable tugging on the 
part of the wasp. 
Before the caterpillar is pulled in it is dragged over to the nest 
and laid down with its head nearest the entrance. Then the wasp 
backs down, grasps her prey with her mandibles and pulls it in. 
Ammophila usually remains inside five to six minutes to arrange 
the caterpillar and to lay the egg. Tigs. 18 and 22 show the posi- 
tion of the egg (4 mm. in length) of one wasp which fixed it on the 
10th segment from the head. The position varies anywhere from 
the 6th to 10th segment. The egg is always securely attached by 
one end (the head end of the embryo) to the side of the cater- 
pillar and points with its free end towards the caterpillar’s venter. 
When the larva hatches it occupies the same position that the egg 
did. It merely pierces the skin at the old point of attachment to 
suck the caterpillar’s juices. 
Ammophila now proceeds to close up the tunnel and leave her 
offspring to its fate. The tunnel is usually closed very carefully; 
some individuals are more or less careless, however, as were Nos. 
72 and 73 whose nests are represented in Fig. 17. One nest was 
left open, the other was closed in a very perfunctory manner. 
Ammophila searches in a radius of a yard and picks up large and 
small pieces and carries them to the nest (Fig. 8). If the piece is 
too large the wasp may carry it to the nest and try to fit it in or 
may discard it before she gets to the nest. She seems to have the 
power of judgment to a certain degree, for she evidently is able 
to determine whether a thing is too large to suit her use or not. 
Not only is debris thrown into the nest but the wasp alternates by 
scratching in the loose sand at the surface and tamping it down 
with her head. When the nest is full enough for the wasp to reach 
down comfortably she presses the separate pieces firmly down before 
she lets go and accompanies the strenuous operation with a cheer- 
ful buzz. Now it sometimes happens, especially towards the end of 
the operation, that a piece of wood is pressed down tightly, then 
pulled out and pressed down again and this repeated several times, 
so that one might suspect that the wasp were here improvising a 
tool with which to tamp down the sand. Indeed this very act was 
observed by the Peckhams and Dr. Williston on Ammophila urraria 
and Ammophila Yarrowi. In each of these two cases the wasp 
used a pebble to tamp down and smoothe over the ground, not once 
merely, but several times, laying the pebble aside each time while 
she brushed on more sand. The use of the piece of wood by Ammo - 
