A WEEK WITH A MINING EUMENID. 171 



CONCLUSIONS. 



1. The habitat of Odynerus dorsalis is a level, or practically level, 

 tract of barren or almost barren land situated conveniently to a 

 supply of water and of Hesperid caterpillars. 



2. The nests are constructed in the ground ; they are vertical and 

 consist of one to three, usually two, cells, which are separated from 

 each other by clay partitions. In rare cases the number of cells 

 may be larger than this. 



3. They occur in colonies of moderate size. 



4. In order to work the clay it is wet with water obtained by the 

 wasp from some near-by stream, or pond, or puddle. 



5. In excavating the nest the wasp works the soil into balls and 

 carries it out of the nest. Normally she flies with the pellet to a 

 distance of from two to twenty-four inches, but if overhanging 

 vegetation or other impediment renders flying with a burden un- 

 pleasant, she walks and deposits the pellets in one or more piles. 



6. During the periods of excavating and of storing the nest the 

 wasp is guided by landmarks ; this is evidenced by the fact that any 

 changes in the surface of the ground always serve to make it diffi- 

 cult for her to locate the nest. 



/. The eggs are attached to the roof of the cell by means of a 

 short thread. There seems to be no definite stage in the provision- 

 ing of the nest for the oviposition. At that time the wasp backs 

 into the cell to lay and then walks out head first. 



8. The Hesperid caterpillars with which she stores her nest are 

 packed in until the cell is full. Since the cells are not all of the 

 same size, the number of caterpillars in the cells varies. In all of 

 the nests examined by me the lower cell is the larger. 



9. In all of the cells examined by me the caterpillars were active 

 enough to squirm when exposed to the light and the air. 



10. If, during her absence to get water, pellets of mud or bits 

 of weed stems are dropped into her nest, the wasp, on returning, 

 removes them and deposits them on the ground near the nest. If 

 paralyzed caterpillars are dropped into such a nest, under the same 

 conditions, the wasp will fly with them to a distance of several 

 yards. 



11. If caterpillars captured by another wasp of the same species 



