230 KANSAS UNIVERSITY SCIENCE BULLETIN. 



quite uniform in structure, but may not be more than one and 

 one-half inches deep and less than two inches long. 



The orthopterous prey of Priononux atrata is rather varied. 

 As far as observed, the victims were always mature and 

 usually of the smaller species of Melanoplus (including laki- 

 nus). A large specimen of atrata was observed by one of the 

 members of the Entomological Survey of 1911, with a 5 

 Melanoplus dijfcrcntiaUs, an insect of considerable strength 

 and magnitude. The author took an atrata in Seward county 

 which had captured a 5 Mermiria neomexicana. 



While the evidence at hand is incomplete, it seems more than 

 probable that the common red-banded bembecid wasp, Stiziis 

 unicinctus Say, plays the pai't of a burglar and uses the locust 

 captui'ed by Priononyx atrata as food for her own young. 

 Unicinctus is a rather compact insect, somewhat inferior in 

 size to and less powerful than the sphecid. It occurred plenti- 

 fully in western Kansas, where it was sometimes seen flying 

 low over the ground, alighting now and then as if inspecting 

 the locality for a nest of some sort. In Stanton county one of 

 these wasps was observed to hover about a freshly made tunnel, 

 apparently that of a Priononyx. which it entered while the 

 sphecid was away. The latter had brought an Aitlocara near 

 this burrow, which, being occupied by Stizus, was finally de- 

 serted by the disgusted Priononyx. 



In Morton county, July 7, 1911, I came upon Stiziis uni- 

 cinctus engaged in smoothing over a spot with her feet. I un- 

 earthed what proved to be a filled-up burrow, which in form 

 and dimensions resembled that of a Priononyx. In the single 

 cell lay a Melanoplus. But where the Priononyx egg was to be 

 expected on this locust was only a small bit of soft matter, 

 probably the remnant of the specid egg destroyed by the 

 Stizus, while cephalad of these remains was a short wasp egg, 

 doubtless that of Stizus. 



Certainly the short-legged Stizus unici)tctus does not appear 

 to be a sufficiently powerful insect to capture and subdue 

 locusts of the size and vigor as those which serve as the prey 

 of Priononyx. 



Further observation upon the interrelation of these two 

 in.sects is needed, so that their complete life history may be 

 brought to light. Although much has been written on the 

 solitary bees and wasps, the data on their postembryonic devel- 

 opment is exceedingly meager, and no doubt ofl'ers a wide and 

 interesting field for the investigator. 



