PREFACE 



The British Oak is the abode of a vast concourse 

 of dependents. Nearly five hundred different species 

 of insects, and other creatures, find their needs amply 

 supplied, mainly by the leaves. Of this number 

 about two hundred are either parasites living upon 

 the larvae of fifty-four species of Cynipidge which 

 produce galls, or they are inquilines obtaining their 

 nourishment from the tissues of the galls. The Oak 

 is therefore of great importance to insect life. 



The object of this volume is to describe and illus- 

 trate, in some measure, galls produced by the Cynipidge 

 and other causes of galls on the Oak. The insects, 

 with their parasites and other occupants of the galls, 

 have been fully described by various writers ; several 

 pages will, however, be devoted to a few interesting 

 and unique features of the Cynipidge. This volume is 

 also the fulfilment of an intimation contained in the 

 preface of my ' British Vegetable Galls,' explaining 

 the reason why galls on the Oak were not described 

 in that work. 



I trust the information herein contained may be the 

 means of assisting many students to a further under- 

 standing of the subject ; that collectors of these most 

 interesting and dainty galls will be enabled to identify 

 any specimen obtained ; and, that casual observers 

 will find in the illustrations and the text, such as will 

 influence them to pursue the study in a practical 

 manner. 



There is much more to be ascertained concerning 



