THE CULTIVATION OF THE OAK 



165 



own galls also, those on the American oaks differing 

 from those on the European species, bat some are common 



FIG. 51. An oak-ieaf with several kinds of Cynips galls 

 on it. a, gall produced by Cynipsscutellaris; b, C. divisa; 

 c, Neuroterus Reawnmril; e, Biorhiza renum; f, Neuro- 

 terus ostreus. (Frank.) 



to more than one species. The insects which produce 

 the commonest English oak-galls are nearly all members 

 of the Cynipidece, a group of hymenoptera which lay 



