THE APPLE-TREE LOUSE. 
243 
the spring of the year like little specks of mould on the 
trees (Fig- 92). As the season advances, and 
the insect increases in size, its downy coat be- 
comes more distinct, and grows in length daily. 
This down is very easily removed, adheres to 
the fingers when' it is touched, and seems to issue 
from all the pores of the skin of the abdomen. 
When fully grown, the insects of the first brood 
are one tenth of an inch in length, and, when 
the down is rubbed off, the head, antennae, suck- 
er, and shins are found to be of a blackish color, 
and the abdomen honey-yellow. The young are 
produced alive during the summer, are buried in masses of 
the down, and derive their nourishment from the sap of the 
bark and of the alburnum or young wood immediately under 
the bark. 
The adult insects never acquire wings, at least such is 
the testimony both of Hausmann and Knapp, and are des- 
titute of honey-tubes, but from time to time emit drops of 
a sticky fluid from the extremity of the body. These insects, 
though destitute of wings, are conveyed from tree to tree 
by means of their long down, which is so plentiful and so 
light, as easily to be wafted by the winds of autumn, and 
thus the evil will gradually spread throughout an extensive 
orchard. The numerous punctures of these lice produce on 
the tender shoots a cellular appearance, and wherever a 
colony of them is established, warts or excrescences arise 
on the bark ; the limbs thus attacked become sickly, the 
leaves turn yellow and drop off ; and, as the infection 
spreads from limb to limb, the whole tree becomes diseased, 
and eventually perishes. 
In Gloucestershire, England, so many apple-trees were 
destroyed by these lice in the year 1810, that it was feared 
the making of cider must be abandoned. In the North of 
England the apple-trees are greatly injured, and some annu- 
ally destroyed by them, and in the year 1826 they abounded 
