HUNTERS OF LARGE ORTHOPTERA 189 



hovering around the wreck of the tunnel, although both 

 hopper and wasp were now gone. How did they know ? It 

 did not any longer look in the least like a P. atratum hole, 

 all dug up as it was. Did some Priononyx odor remain on 

 the dirt which she had handled, by which the parasites, and 

 also Stizus, could detect the location? 



On one other occasion we opened a carelessly closed, or, 

 as we later concluded, a newly opened burrow which we 

 took to be that of a P. atratum, but .were surprised to find, 

 beneath the rumpled earth-covering, a freshly-killed hopper 

 and in the chamber with it a live Stizus. What business she 

 had there we can only surmise. 



To be sure, the above cases give only circumstantial evi- 

 dence, which is generally not accepted as proof in the 'courts 

 of law. Yet we think that the evidence here is strong enough 

 to justify our indicting Stizus as a cow-bird wasp, and one 

 highly skilled in her profession. In this suspicion we are 

 not alone, for Williams also has suggested : 



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

 than probable that the common red-banded bembecid wasp, 

 Stizus unicinctus Say, plays the part of a burglar and uses 

 the locust captured 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. . . . 

 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 Auiocara near this burrow, which, being 

 occupied by Stizus, was finally deserted by the disgusted 

 Priononyx. 



"In Morton county, July 7, 1911, I came upon a Stizus 

 unicinctus engaged in smoothing over a spot with her feet. 

 I unearthed what proved to be a filled-up burrow, which in 



