HYMEXOPTERA. 



241 



before they are ready to form their cocoons, so that 

 the insects must be stung in the right place and sim- 

 ply paralyzed ; if killed, as they sometimes are, de- 

 composition takes place, and they become not only 

 unfit for food, but are apt to be dangerous in other 

 ways to the health of the larvae confined in the same 

 cell. Sphex represents the fossorial Hymenoptera, 



Fig- 193- 



such as the Mutillidae (" solitary ants ") and Pompi-^ 

 lidae ("sand-wasps "). Among the latter is the inter- 

 esting "tarantula-killer," or " tarantula- hawk," PoiJipi- 

 lus formosus, of Texas and Arizona. Specimens of 

 this wasp, and the great spider, Afygale Hentzii (erro- 

 neously called tarantula), which it paralyzes, can be 

 sent by mail to Eastern teachers. It is a powerful 

 wasp as compared with our hornets. The body of 



