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Insect Architecture. 



CHAPTER XIX. 



STRUCTURES OF GALL-FLIES AND APHIDES. 



"11 ANY 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 atten- 

 tion 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 in the 

 established systems of classification ; though the latter has 

 been recently much improved by Mr. Westwood. 



Small berry-shaped galls of the oak leaf, produced by Cynips quercus folii ? 



One of the most simple and very common instances of the 

 nests constructed by gall-insects, may be found in abund- 

 ance during the summer, on the leaves of the rose-tree, the 

 oak, the poplar, the willow (Salix viminalis), and many other 



