THE CULTIVATION OF THE OAK. 



165 



own galls also, those on the American oaks differing 

 from those on the European species, but some are com- 

 mon to more than one species. The insects which pro- 



FIG. 51. An oak-leaf with several kinds of Cynips galls on it: a, gall 

 produced by Cynips seutellaris ; J, C. divisa ; c, Neuroterus Reau- 

 murii; e, BiorJiisa renum; f, Neuroterus ostreus. (Frank.) 



duce the commonest English oak-galls are nearly all 

 members of the Cynipidece, a group of hymenoptera 

 which lay their eggs in the young tissues of various 



plants, especially oaks and roses. 

 12 



