360 CARL HARTMAN 



examined the nest to see if the bottom had not fallen out ! But 

 caterpillars continued to be pushed in until the feat seemed 

 almost uncanny. Nest No. I held twenty-four; nest No. II, 

 twenty caterpillars. 



Following are the times that wasp No. I returned with her 

 twenty caterpillars — Aug. 12th: 9:30, 9:37, 10:00, 10:50, 11:10, 

 11:17, 11:35, I:i °. 2:I 5> 3'- 10 , 3-'26; Aug. 13th: 8:15, 8:40, 

 8:48, 9:07, 9:30, 10:20, 10:36, 10:46, 11:00. The variable time 

 required to obtain the prey (6 to 65 minutes) indicates the 

 large part that chance plays in the finding of the prey. 



The caterpillars stored by Eumenes belfragei are Geometrids, 

 the largest of which exactly fit into the lumen of the neck (fig. 

 5). The wasp carries the caterpillar with the mandibles and 

 all the legs, flying with it in and out among the grass blades all 

 the way to the nest. 



In flight, the body of Eumenes is held horizontal. So smooth 

 are the movements that the wasp may be said to sail along, 

 turning to right and to left to avoid obstructions as though 

 guided by a rudder. The flight of the wasp is extremely grace- 

 ful and one that is characteristic of the Eumenidae. To the 

 thorough observer the wasp's general manner of movement is 

 as definite a character of the group as any morphological 

 character. 



It should also be stated that the wasp did not always fly 

 in the same direction when starting out for the hunting grounds, 

 for she passed around the house to the north as well as to the 

 west. 



Nest No. II was opened Aug. 16, when the larva had de- 

 voured all the twenty-four caterpillars stored. The larva soon 

 spun a cocoon of white fibers, which remained white perma- 

 nently. On Sept. 4, twenty-four days after the egg was laid, 

 an adult male emerged. 



From nest No. I was reared a parasite (Microdus (Crassi 

 microdus) sp. nov.). 



The determination of Eumenes was made by Mr. S. A. Rower ; 

 of the parasite by Mr. H. L. Viereck, to each of whom the writ- 

 er's thanks are due. 



