370 



Chapter XIX. 



Structures of Gall-flics and Aphides. 



Many of the processes which we have detailed 

 bear some resemblance to our own operations of 

 building with materials cemented together; but we 

 shall now turn our attention to a class of insect- 

 architects, who cannot, so far as we know, be matched 

 in prospective skill, by any of the higher orders of 

 animals. We refer to the numerous family which have 

 received the name of gall-flies, — a family which, as yet, 

 is very imperfectly understood, their economy being no 

 less difficult to trace than their species is to arrange 

 m the established systems of classification ; though 

 the latter has been recently much improved by Mr. 

 Westwood. 



Small berry-shaped galls of the oall-leaf, produced by Cynips Querent J'olii ? 



