38 



THE OAK. 



this insect feeds on the leaves of one of our 

 Willows : but the perfect insect, according to 

 Haworth, invariably fixes his throne upon the 

 summit of a Broad-leaved Oak, from the utmost 

 sprigs of which, on sunny days, he performs his 

 aerial excursions ; and in these ascends to a much 

 greater elevation than any other insect I have 

 ever seen, sometimes mounting higher than the 

 eye can follow ; especially if he happens to quar- 

 rel ^vith another Emperor, the monarch of some 

 neighbouring Oak : they never meet without a 

 battle, flying upwards all the while, and combat- 

 ing ^vith each other as much as possible ; after 

 which they will frequently return again to the 

 identical sprigs from which they ascended." 



To the class of innocuous insects must be re- 

 ferred also the various species of gall-flies, Vv'hose 

 instinct teaches them to originate a local disease 

 in some part of the Oak, and thus to provide 

 their offspring ^vith food and a dwelling-house. 

 A history of the Oak would be very imperfect 

 mthout a full notice of the curious productions 

 kno\ra by the name of galls; and, as the subject 

 is a very interesting one, I do not scruple to dwell 

 upon it, although, strictly speaking, it belongs as 

 much to Entomology as to Botany. 



A small fly alights on a Uvig, or leaf, or bud, 

 of an Oak, and with an excessively acute instru- 

 ment, with which it is provided by Xature for this 

 express purpose, punctures the vegetable fibre, 

 and deposits an egg, or perhaps two or more eggs, 

 so minute as to be almost invisible to the human 

 eye. And is this all the provision that the fly is 

 going to make for its progeny ? It is ; for though 

 seemingly little, it is ample enough. The pre- 



