106 PEAR. LIMBS — PEAR BARK-LOUSE. 



color, adhering to the bark on the under sides of the limbs, par- 

 ticularly of young trees which are growing thriftily. These 

 scales are the relics of the dead females covering and protecting 

 their young. Some are of a darker color than others, and smaller 

 ones occur which are of a dull yellow hue. These scales are not 

 freckled with paler spots like many of our species of bark-lice; 

 their surface frequently presents shallow identations as though 

 it had been slightly pressed upon in places Avith the head of a 

 r~ — i pin, and the outer margin is wrinkled, as shown in 

 'Jl^, accompanying figure, and is sometimes marked with 

 [ faint black bands. If one of these scales is removed 

 ^'j a round white spot the size of the scale remains upon 

 the bark, appearing as though made with chalk. Upon the un- 

 derside of one small twig, in a distance of nine inches, thirteen 

 of these scales occurred and five white spots where other scales 

 had been rubbed off. 



4 



At the time when I noticed these scales the young lice under 

 them were active and so minute that they appeared to the eye 

 like particles of dust. I conveyed a twig to my residence and 

 bound it to a thrifty limb of a young apple tree, to ascertain 

 whether they could subsist upon this tree; but they all perished, 

 not one of them leaving the pear twig, that I could discover. The 

 following May the chalk-like spots where the scales had been 

 fixed upon the twig were still distinct, the storms and frosts of 

 autumn and winter having scarcely dimmed them in the least. 



Beneath the scales the young lice are interspersed through a 

 mass of white cotton-like matter. This subsequently increases in 

 volume and protrudes from under one end of the scale, elevating 

 it from the bark, as shown in the annexed cut. The 

 young lice now crawl out from among this matter and 

 diffuse themselves over the smooth bark, appearing to 

 the eye like minute whitish specks or fine dots. When 

 magnified they are found to be of an oval form, somewhat flat- 

 tened, about the hundredth part of an inch in length, and two- 

 thirds as broad as they are long. They are of a dull white color, 

 with six legs and two short antennse of a hyaline-white appear- 

 ance. The antennge are thread-like or of equal diameter through 



