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XIV. On Tivo Species of Insects which are found injurious to 

 the Pear Tree. By Thomas Andrew Knight, Esq. F. R. S. 

 President. 



Read April 19, 1836. 



1 he leaves of Pear Trees which are trained to walls, have sus- 

 tained, during some years, much injury in many gardens, from the 

 depredation of the larvae of a very minute species of moth, the 

 Tinea Clerckella of Linnaeus : and I have been informed that it 

 abounded in the Royal Gardens at Kew in the last summer. The 

 Moth appears in the end of May and the beginning of J une ; and 

 it is readily distinguished by the silvery whiteness of its wings, 

 which are tipt lightly with brown, and by its small size, its length 

 scarcely exceeding a single line. It is an extremely pretty little 

 insect, and possesses so much activity, that it is difficult to obtain 

 a living specimen of it. It probably deposits its eggs, or, perhaps, 

 more properly, its spawn, upon the under surfaces of the leaves ; 

 and the larvae, having there penetrated through the epidermis, feed 

 upon the internal parenchymatous matter of the leaf. Brown and 

 lifeless circular spots in consequence appear upon the leaves, such 

 as an excess of heat would occasion ; and I have known several 

 gardeners who have supposed it to be caused by solar action. 

 These lifeless spots enclose the larvae of the Moth abovementioned, 

 which do not exceed a line in length. Whenever the leaves of a 

 Pear Tree contain many of these, the fruit does not acquire nearly 

 its natural size, and it ripens without acquiring either sweetness or 

 flavour. 



This insect is an old inhabitant of our gardens : I first observed 

 it half a century ago, but it appears latterly to have become much 



