650 THE STUD Y OF INSECTS. 



Family POMPILID^; (Pom-piri-dae). 

 The Spider-wasps. 



The spider-wasps are so called because they provision 

 their nests with spiders. They are slender in form, with long 

 legs (Fig. 771), and are usually black with 

 dusky reddish or black wings ; sometimes 

 they are variegated with red or orange. The 

 peduncle is short, so that the abdomen is very 

 closely united to the thorax. Many of the 



FIG. 771. Potnpilus . . .. 



species are ot medium size, but some are very 

 large. In fact, the largest of all known Hymenoptera belong 

 to this family. 



One of the giants of the family is the well-known Taran- 

 tula-hawk, Pepsis formosa (Pep'sis for-mo'sa), of the South- 

 west, which stores its burrows with Tarantulas. Many a 

 hard-fought battle does this digger-wasp have with these 

 enormous spiders; and sometimes it is conquered and igno- 

 miniously eaten. 



Most of the Pompilidae dig burrows in the ground ; but 

 some species of Agenia (A-ge'ni-a) make cells of mud attached 

 to the lower surface of stones or in the chinks of walls ; and 

 the members of the genus Ccropalcs (Ce-rop'a-les) are inqui- 

 lines in the nests of other digger-wasps. 



About one hundred and twenty species belonging to this 

 family are known in our fauna. 



Family SPHECID^E (Sphec'i-dae). 



The Sphecids (Sphe'cids) or the TJiread-waisted Wasps. 



These are the most commonly observed of all our 

 digger-wasps as certain species build their mud nests in the 

 attics of our houses ; and, too, the peculiar shape of the 

 body makes them very conspicuous. The Sphecidae differ 

 from the preceding families of digger-wasps in that the pro- 



