2. THE PEAR. 



AFFECTING THE LIMBS. 



A hemispherical chestnut-brown scale, the size of a half pea, upon the under 

 sides of the limbs the latter part of June. 



The Pear Bakk-louse. Lecanium Pyri, Scheank. 



As the pear is so closely related to the apple, most of the in- 

 sects which affect one of these trees will be found upon the other 

 also. We have already noticed this fact in repeated instances 

 when considering the insects of the apple tree. But in addition 

 to those species which are common to both, there are others 

 which are limited to one of these trees and never invade the other, 

 except perhaps in those extreme cases when they become so mul- 

 tiplied upon their appropriate tree that it fails to afford suflacient 

 room and nourishment for all the individuals which are called 

 into existence. 



Of those insects which are peculiar to the pear, the only one 

 which has as yet fallen under my notice is a species of bark-louse, 

 which, it is altogether probable, is the same which occurs upon 

 this tree in Europe, named Coccus Pyri by Schrank (Fauna Boic. 

 ii. 1. 145), and which pertains to the modern genus Lecanium in 

 the Family Coccidjs and Order Homoptera. This insect had 

 never been publicly noticed as an inhabitant upon this side of the 

 Atlantic, that I am aware, when, upon the first of July, 1854, I 

 met with it quite common upon pear trees in the cities of Albany 

 and Troy. I obsierve, however, that Dr. Harris, in his discourse 

 before the American Pomological Society in September last (page 

 8), Incidentally mentions the fact that our pear trees " suffer oc- 

 casionally from bark-lice." 



The form under which this insect appears is that of a hemi- 

 spherical scale about 0.30 in diameter and of a chestnut brown 



