190 WASP STUDIES AFIELD 



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 egg was only a small bit of 

 soft matter, probably the remnant of a sphecid egg de- 

 stroyed by the Stizus, while cephalad of these remains was 

 a short wasp egg, doubtless that of Stizus. 



"Certainly the short-legged Stizus unicinctus does not 

 appear to be a sufficiently powerful insect to capture and 

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

 the prey of Priononyx" 



If we consider this idea tenable, it may throw some light 

 upon the circumstances which obtained when once we found, 

 in different places, three open holes, apparently of P. atra- 

 tum. We opened them further; one hopper had been 

 almost all carried away by ants, another was heavily para- 

 sitized by Diptera larvae and nearly riddled, and the third 

 had both ants and parasitic larvae. Had Stizus opened 

 these and left them open like the one described above? We 

 have at other times also been mystified by open Priononyx 

 holes or their grasshoppers ruined by ants. Some such 

 cause must be behind this waste, for it is too frequent to 

 be attributed to mere accident. Furthermore, when Pri- 

 ononyx closes her hole, she does it so thoroughly that it 

 takes a sneak-thief to get in. 



Stizus undoubtedly opens the nests for the purpose of 

 laying her own egg. True, we have not found her egg 

 there, even though the Priononyx egg had been destroyed, 

 but this may well have been due to our faulty manipu- 

 lation in digging. It seems hardly possible that the taste 

 of Stizus can be so perverted that she, cannibal-like, goes 

 into the nest only for the purpose of sucking the contents of 

 the egg, for we find she is a nectar-feeeder. We have often 

 seen her feeding upon the flowers of white snakeroot. 



