THE CULTIVATION OF THE OAK 165 
own galls also, those on the American oaks differing 
from those on the European species, but some are common 
Fig. 51.—An oak-leaf with several kinds of Cynips galls 
on it. a, gall produced by Cynips scutellaris; b, C. divisa; 
c, Neuroterus Reaumurii; 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 Cynipidee, a group of hymenoptera which lay 
