16 Some Solitary Wasps of Texas. 



whether the tunnel is large enough to admit the caterpillar, for the 

 wasp always, before pulling the caterpillar in, brings out a number 

 of mouthfuls of earth and on each trip approaches the caterpillar 

 as if to measure its thickness. Sometimes only a few, and some- 

 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 witli her mandibles and pulls it in. 

 Ammophila usually remains inside five to six minutes to arrange 

 the caterpillar and to lay the egg. Figs. 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 dovm 

 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 



