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 Bark-louse. Lecanium Pyri, Sciirank. 
As the pear is so closely related to the apple, most of the in¬ 
sects which aifect 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 sufficient 
room and nourishment for alii 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 CocciDiE 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 observe, 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 0.20 in diameter and of a chestnut brown 
