WHEELER— THE PARASITIC ACULEATA. 15 



including in my survey. The following are the only cases I have 

 found in the literature. According to Ferton (1901) the Gorytid 

 Nysson diiiiidiafits is a parasite of Gorytcs elcgans. The latter digs 

 its burrow in the sand and provisions it with larval and adult Hem- 

 iptera; the N\sson finds it and often enters it during the absence 

 of the Gorvtes. If the latter happens to be at home the Nysson 

 waits motionless about a dozen centimeters away, with its head 

 turned towards the nest, till the Gorytcs departs. Adlerz (1910) 

 observed very similar behavior on the part of Nysson maculatus 

 towards Gorytcs lunatus. Apparently both species of Nysson de- 

 stroy the Gorytcs egg attached to the prey and lay their own in its 

 place. In 1887, at a time when nothing was known of the parasitic 

 habits of Nysson, Handlirsch called attention to the superficial re- 

 semblance of some of the species to parasitic bees. 



Williams (1913) and the Raus (1918) have described an inter- 

 esting sporadic case of parasitism in Sticus unicinctns, a wasp be- 

 longing to a very different family, the Bembicidse. The Stiziis digs 

 its way into the nest of a Sphecid, Chlorion thomcr, after the latter 

 has provisioned it with a cricket, oviposited and closed the entrance. 

 After the Bembicid has entered the chamber it devours the Chlorion 

 egg and deposits its own so that the larva can have the cricket all 

 to itself. This case is extraordinary because the other species of 

 Stisns {S. tridcns and crrans) , whose habits have been studied by 

 Fabre (1886) and Ferton (1899, 1908, 1910, 191 1), dig their own 

 burrows in the sand, glue their egg to the bottom of the cell and 

 feed the hatching larva continuously with Hemiptera after the man- 

 ner of other Bembicids (Bicyrtcs). Ferton has also observed 

 similar behavior in S. gazagnairci and fcrtoni. According to the 

 same observer (1899, 1901, 1908) S. fasciatns feeds its young with 

 immature crickets. Our American Stizus with the exception of 

 unicinctns, seem to have similar habits. During the summer of 

 1 91 7 I saw a flourishing colony of a small undetermined species 

 near Tempe, Arizona. It comprised thousands of individuals, all 

 nesting close together in the sand, like Bcmhix. 



The remaining parasitic wasps belong to the family Psammo- 

 charidse (Pompilidse), all of which prey on spiders. In two of his 

 papers (1890, 1891) Ferton has shown that some individuals of 



