Some Solitary Wasps of Texas. 7 



reach, took a second hold and pushed it on further, repeating the 

 operation until the whole length of the caterpillar was inside. 

 Then she crawled up and with her head stuffed all the caterpillars 

 as far back into the chamber as possible. This done, she cleaned 

 her antennae and flew away without seeming to take her bearings. 

 She had evidently made so many trips to the spot that a study of 

 the locality had become unnecessary. 



By 7 p. m. the cell had been closed and another built, which 

 the wasp was occupying for the night. A day's work with dorsalis 

 evidently consisted of storing a cell, closing it, and building another 

 to be used in the first instance as a lodging place for the night. 

 Thus I found her still at home at 7:45 the next morning (Sep- 

 tember 4th), as shown in Fig. 4. She was lying in the cell, which 

 her body comfortably filled, and was amusing herself with picking 

 up unwary ants that chanced to pass too close to her threshold 

 and, like the Harpies of old, grinding them in her jaws. I allowed 

 her to store this cell, as well as build another; then I caught her 

 and carried the cells home. 



0. dorsalis. builds pretty mud-cells on the ground, choosing a 

 place hidden from view by a clump of grass. The cells are broadly 

 spindle-shaped, pointed at one end, which is left open until the 

 cell is stored. The chambers do not touch each other for more 

 of their length than is necessary for their mutual agglutination. 

 This almost entire independence of the cells entails a considerable 

 waste of building material as compared with the habit of Pelopaeus 

 cementarius, which builds her cells side by side in rows 

 and tiers of rows. It seems probable that the former method is 

 the more primitive one, and that the latter has been superinduced 

 by the mud-dauber's habit of building on flat surfaces. It is to 

 be noticed that the lumen of a mud-dauber's cell still remains, in 

 spite of the irregularity of the outer surface, cylindrical. The 

 entire structure* made by dorsalis is not only held together by the 

 slight adhesion of the more or less fragile cells which compose it, 

 but is also partially suspended by grass-roots imbedded in the 

 plastered walls. The shape of this nest with the grass-roots at- 

 tached can best be seen in the figures which are photographs taken 

 at different stages in the construction. (Figs. 3, 4, 10, 11.) 



The first wasplet emerged on October 7th, the others on October 

 8th, 9th, and 11th, respectively. One wasp failed to emerge and 

 was probably from the fourth egg laid, and would normally have 

 emerged on October 10th. If one cell was stored each day, the 



