PREFACE. IX 



Forest Trees,' by Mr S. L. Mosley, Huddersfield, and the 

 splendid ' Manual of Injurious Insects ' by the late Miss 

 Ormerod. Of the latter I cannot speak too highly, more 

 especially as Miss Ormerod gave me very great encourage- 

 ment by correspondence. 



As the period during which I have studied the subject has 

 extended over twenty years, it is obvious that much original 

 work has been done by many workers during that time. 

 I have tried, so far as means or leisure would afford, to keep 

 in touch with all original work. In order, therefore, that the 

 student may get the full advantage of that, I have, whenever 

 I found the work of others more suitable than my own, 

 quoted from those writers. In most cases this has been done 

 by direct permission of the author, but in all cases when 

 giving an extract I have endeavoured to duly acknowledge 

 the same. In this advanced age of ours, knowledge, more 

 especially Entomological knowledge, is no longer the prop- 

 erty of any one individual. Hence all quotations are freely 

 given as epitomised knowledge suitable for the student. 

 They are given to obviate at first the necessity of consulting 

 other works, and yet at the same time be a guide as to what 

 other works he may consult for fuller information. It will 

 be apparent that the majority of quotations are of a systematic 

 nature. Hence the great difficulty in preparing the book has 

 been to amalgamate the systematic with the economic, and so 

 maintain a due proportion. On the one hand, if too many 

 details of a systematic nature were given, the work would not 

 only have been very much overladen, but the practical man 

 would be impatient in reading it : on the other hand, if too 

 few systematic details were given, it would not act as a guide 

 to fuller inquiries, or form, as designed, a suitable text-book 

 for students at agricultural and other colleges. The main 



