OF WASHINGTON, VOLUME XVII, 1915 71 



Wasp No. 55 was observed running excitedly about over the 

 sand with her abdomen arched and her wings flipping nervously 

 in a manner that characterizes this species when seeking a place 

 for a nest after having captured a caterpillar. She digged her 

 nest about fifteen feet from the point where she had left her 

 caterpillar lying in a clump of weeds. When the nest was com- 

 plete and the wasp had gone to bring her caterpillar I placed my 

 camera in position at the nest. The wasp quickly returned with 

 her caterpillar arid when she had taken it inside I reached down 

 into the nest with a pair of forceps and pulled it out again. The 

 wasp came out of the nest, stepped astride the caterpillar and 

 bending her abdomen beneath the thorax inserted her sting on 

 the ventral side. She then took the caterpillar inside as before 

 and I promptly pulled it out again. This time she came out and 

 with her mandibles seized the caterpillar, which was lying dorsal 

 side up, and inserted her sting on the ventral side of the abdomen 

 five successive times, each time in a different segment proceeding 

 backward from the first or second. Once more she took the 

 caterpillar inside the nest and again I pulled it out. This time, 

 however, she held on to her prey and I pulled her out too. 



She at once picked up her caterpillar and started off with it. 

 After carrying it about aimlessly for a few minutes she placed 

 it amid some grass near by and began the construction of a new 

 nest some distance from the first one. It required just nine 

 minutes for her to complete this nest. When she had it finished 

 she returned to her caterpillar and took it inside the new nest. 



In the meantime a number of parasitic flies had discovered the 

 wasp and her prey. So far as my experience goes these flies do 

 not pay any attention to the caterpillar so long as the wasp is 

 not near it; but just as soon as she begins to work with it they 

 seek to place their young upon it or to place them in the entrance 

 to the nest. Since I wished to rear this wasp from the egg I 

 was kept busy chasing the flies away. When the wasp entered 

 the new nest I succeeded in driving all the flies away except one, 

 which I was obliged to capture and which Dr. C. H. T. Townsend 

 finds to be a new species belonging to the genus Hilarella. 



As soon as the wasp had emerged and sealed up the nest I 

 digged it up and after making a photograph of the egg in place 

 on the caterpillar (fig. 2) I placed them in a glass-covered plaster 

 breeding cell and buried the outfit to the depth of an inch below 

 the surface of the sand in the garden. On the morning of July 

 22 the egg showed no evidence of hatching but on the following 

 morning at the same hour the larval wasp was feeding on the 

 caterpillar (fig. 3). In the case of this species the head of the 

 larva develops at the end of the egg attached to the food provided 

 by the mother wasp, just the reverse of what takes place in the 



