1 68 C. H. TURNER. 



behavior of these wasps is identical with that of those into whose 

 nests I had introduced caterpillars that had been captured by other 

 wasps. It seems reasonable to assume that these caterpillars have 

 been deposited in the nest by some other wasp. 



TIME REQUIRED TO PROVISION THE NEST. 



Isely found ('14) that many of the specimens examined by him 

 excavated, provisioned, and sealed the burrows in less than two 

 hours, although some of the individuals took a day for the work. 

 In every case that I followed from beginning to the end the wasp 

 always constructed the burrow one day and sealed it on the after- 

 noon of the next day or the morning of the day after. Thus the 

 time elapsing from the beginning of the excavation to the final 

 sealing of the nest was twenty-four hours or more. Since the 

 amount of time consumed in excavating the burrow was about the 

 same in each case, the greater length of time required by my wasps 

 to complete the work may have been due to lack of food. Isely's 

 colonies were located where the mallow was abundant; my wasps 

 were situated near a large field of field sorrel, scattered through 

 which were a few mallow plants. On one occasion I followed a 

 wasp, from plant to plant, for more than half an hour. She exam- 

 ined leaf after leaf, without finding any caterpillars. I uncoiled 

 several leaves, but found them empty. 



CAPTURING THE PREY. 



i 



Isely ('14, p. 289) writes as follows: "When O. dorsalis would 

 come upon a crumpled leaf containing the larva of the spotted 

 skipper, she would commence tearing energetically at the silken 

 nest, first at one end and then at the other. Although the wasp 

 worked furiously and without pausing, sometimes more than five 

 minutes were required to dislodge the caterpillar. Usually, how- 

 ever, in less than a minute the caterpillar would be jerked violently 

 from the cover, seized by the neck, and stung two or three times 

 under the thorax. Once I saw a wasp seize a caterpillar by the 

 tip of the abdomen, to jerk it out of the nest, and sting it under 

 the last abdominal segments. Then she quickly seized the neck 

 and gave it three thrusts under the thorax. A vigorous malaxation 



