THE INSECTS OP THE GREEN LANES. 195 



another class of objects, which occur as parasites or 

 as malformations. The galls clustering so thickly on 

 pollarded oaks, and the " spangles " or " buttons " 

 which may often be seen almost covering the backs 

 of leaves, are both the work of certain insects which 

 rnpture the epidermis, and cause the cellular vege- 

 table matter to assume these monstrous shapes. The 

 same cause is assignable to the " bedeguar," the 



Fig. 137. 



Gall Insect (Cynips Kottari), X 10. 



rough red, furry knots so often to be seen on the 

 wild rose. The common gall of the oak is produced 

 by the female of a little fly known to entomologists 

 by the name of Cynips Kollari. A great many 

 curious discoveries have recently been made 

 concerning the little-studied gall insects. The 

 females are parthenogenetic i.e. they can breed for 

 several generations without the aid of the males. 

 They are also dimorphic i.e. the broods from the 



o 2 



