3 88 ORDERS OF PTILOTA. 



The family Tenthredinidce are termed saw-flies, from the 

 peeuUar saw-Uke constructiou of their ovipositor, above 

 described ; they are vegetable feeders. The Pupivora, on the 

 contrary, are parasites, the cuckoo-flies {Ichneumonidce) being 

 eminently serviceable in checking the too great increase of 

 caterpillars and other plant-feeding insects. The Cynipidce, 

 however, or gall-flies, are vege- 

 table feeders, the females form- 

 ing galls upon various plants? 

 as above noticed. The family 

 FormicidcB comprises the nu- 

 merous tribes of ants, of which 

 the Atta cephalotes, or visiting 

 ant, already figm-ed above, the 

 Formica fusca, or brown ant, 



AphidiusRos. depositing Us eg,s in the h^rC figUrcd mth PohjerCfUS 



plant lice. 1. natural «ize, and 2, magnified, ^^ff^gccns, a remarkable spccics 

 which lives in small colonies, making captives and slaves of 

 the Formica fusca, may be mentioned as examples. This 



, Polyergus rufescens b, Formica fusca. 



family, like all the other tribes of insects living in society, 

 through their diff'crent states consists of three kinds of indi- 

 viduals, — males, females, and neuters. 



