336 TEXTBOOK OF ZOOLOGY 



ging the hole for the nest and gathering the provisions is appar- 

 ently done entirely by the female. At no time was the male seen 

 to engage in any part of this work. After the nesting is begun the 

 females spend the night in the burrows with the head uppermost, 

 while the males roost upon nearby herbs or shrubs. 



"Their attempts at copulation are very amusing as well as in- 

 teresting. Beginning about one or two o'clock in the afternoon the 

 males become very active. They fly rapidly back and forth over 

 the community usually from six to eight inches above the ground. 

 They often alight on a female as she is working about the nest or 

 returning to the nest with food and knock her to the ground. One 

 female was resting on the ground when a male flew down and 

 alighted on her back as if attempting to copulate; another male 

 attacked with such vigor that the female flew away with still an- 

 other male in pursuit. 



"The ground where the nests are made is hard, dry, and com- 

 posed principally of clay. In order to penetrate it the female fills 

 a thin pouchlike sac, located within the second segment of the ab- 

 domen, with water and uses this to moisten the ground. With her 

 mandibles she digs the dirt out in small pellets, varying in size from 

 2 mm. in diameter to 6.8 mm. These pellets are carried a short 

 distance away from the hole. This work is continued until the hole 

 is as deep as desired, the depth varying from 48 to 110 mm. There 

 are usually one or two, rarely three, cells constructed in the tunnel 

 for the deposition of eggs. The bottom of the hole is enlarged 

 slightly into a cell and is made very smooth on the inside. The 

 cell might be lined with a secretion from the body which forms a 

 cementlike protection to the larva during the winter. The average 

 size of the cells is 23 by 14 mm. In general they are ovoid-elliptical 

 in shape. 



"Each cell is provisioned with from five to twelve Pieridae larvae. 

 The wasp carries these larvae by grasping them with her mandibles 

 just back of the head and supporting them somewhat with her two 

 front legs. Desiring to learn how Odynerus handled the larvae be- 

 fore putting them in the nest, the writer attempted to induce several 

 wasps to pick up worms that were dropped on the ground about the 

 nests. Favorable results were obtained in two cases. When the wasp 

 found the worm she applied her mandibles to various places on the 

 body but spent most of her time biting just back of the head as if 



