2S6 KANSAS UNIVERSITY SCIENCE BULLETIN. 



denly and backed out. For a minute or two she seemed un- 

 decided. Several times she put her head into the burrow but did 

 not enter. Then she located a new nesting site, two and one- 

 half inches from the first one, clearing the ground by sweeping 

 with her front feet, as before. At 11 :19 she brought her first 

 load of water and began work on her second burrow. 



The depth of the deserted burrow, which this wasp had dug 

 in forty minutes, the result of a total of 102 trips for water and 

 for removing earth, was one and three-fourths inches. I could 

 find no cause for the desertion of this nest. 



O. dorsalis worked on the second burrow as industriously 

 as she had on the first, and much in the same manner. At 

 1 :05 P. M. she stopped digging and flew away over the pasture 

 in search of caterpillars, storing six in one hour and five 

 minutes. After depositing the sixth caterpillar she came out 

 of the burrow, then backed into it, staying inside about three 

 minutes — I supposed to oviposit. Then she flew away toward 

 the river, and on returning entered the burrow. Later, when 

 I opened the nest, I found that she had used earth from the 

 sides of the burrow to furnish material with which to seal the 

 entrance to the cell. 



Sealing the mouth of the burrow was the next work. Earth 

 at the edges of the burrow's entrance was moistened, then re- 

 moved and applied to the sides of the burrow's entrance. When 

 enough earth had been removed to completely close the bui*- 

 row a basin-like depression was left. The process of sealing 

 the entrance to the burrow occupied nine minutes. Two trips 

 for water were made, each occupying thirty seconds. 



This wasp had completed the entire work of excavating her 

 nest, storing and closing it in three hours and five minutes. 

 The burrow, which was two and one-eighth inches deep, was 

 excavated in one hour and forty-five minutes. 



One of the wasps I observed dug somewhat faster than the 

 one just described. In one hour and twenty-five minutes she 

 excavated a burrow with one cell, three inches deep, in con- 

 trast to one hour and forty-five minutes required to excavate 

 a burrow two and one-eighth inches deep. For eight and one- 

 half minutes I timed her trips. During that time she went for 

 water four times and removed twenty-two pellets. The trips 

 for water required about the same time as those of the first 

 wasp, but the removal of a pellet of earth required only seven- 

 teen seconds on the average, while with the first wasp this 



