THEIR RELATION TO EACH OTHER 117 



pithy plants, collect plant lice, the larvae of small beetles, 

 flies, or even other Hymenoptera. There is hardly a 

 species so small as not to be attractive to some of the 

 smaller wasps, and on the other hand, the largest Cicada 

 or tarantula is not safe from these formidable enemies. 

 When large species are fed upon, a single specimen 

 often serves to bring a larva to maturity. The "taran- 



FIG. 57. Sphecius speciosus carrying a cicada to its home. 



tula hawk," when it has succeeded in finding a suitable 

 spider, and has succeeded in quieting it with the formi- 

 dable sting, buries its prey and lays a single egg on it. 

 We have quite a number of wasps that do little more 

 than bury their host and lay an egg on it. The hand- 

 some large Sphecius that preys on the Cicadas or dog- 

 day harvest-flies, makes a burrow with several laterals, 

 in each of which it stores a specimen or two which 

 serve to bring to maturity one of the wasp larvae. 

 There is an exotic species living on one of the large 

 roaches, which, after stinging its prey so as to deprive 



