322 WASP STUDIES AFIELD 



immedately after the first was finished, and close beside it. 

 On several occasions, when we began to dig up a nest and 

 scooped off the surface soil with the trowel, the removal 



FIG. 63. The mandible-marks on the tunnel of Odynerus dorsalis. 

 Natural size. 



of the thin layer revealed three or four nests near together. 

 We have only occasionally noticed, in our St. Louis wasp- 

 field, the pretty saucer-like depressions which betray the 

 location of the closed nests. 



One such group of nests particularly impressed us. For 

 a week at least we had been watching a certain O. dorsalis 

 as we crossed the field each morning. On every occasion 



