735 
No. 145.] 
wood, it ceases to eject its castings, and consequently we are then 
left without any clue by which to discover it. Hence the im¬ 
portance of searching for it seasonably. 
A small, oblong, flattish, brown scale, shaped like on oyster shell, fixed to the smooth 
bark; often in prodigious numbers; in winter and spring covering a number of minute, 
round, whitish eggs. 
The Apple Bark-louse, Aspidiotus conchiformis, Gmelin; Coccus arborum linearis, 
Modker, and others; Diaspis linearis, Co.'TA. 
The Bark-louse is, on the whole, the most pernicious and de¬ 
structive to the apple tree, at the present time, of any insect in 
our country. Every where through the northern States it is in¬ 
festing the orchards to a grievous extent, causing the death of 
many trees, and impairing the health and vigor of many more. 
It appears in the form of minute scales, resembling the 
shell of a muscle or an oyster in their shape, adhering to 
the surface of the bark, as shown in the annexed cut. It 
is no rare occurrence to meet with young trees, the bark 
of which is literally covered and crowded with these 
scales from the root to the end of the twigs, and some in¬ 
dividuals finding no vacant spot upon the bark where they can 
fix themselves, are driven to the leaves and the fruit, for upon 
these one or more of these scales may sometimes be found. And 
where a tree continues to be thus infested, year after year, it 
dwindles away and finally dies. I have observed this to be the 
case especially with young trees standing alone in fields, where, 
when the vigor of the tree becomes impaired, the insect has no 
other tree to which it can migrate, better adapted for its suste¬ 
nance. Other trees have been noticed as overrun by this insect 
for a year or two, when, probably from the tree becoming so ex¬ 
hausted as no longer to be capable of suitably sustaining the in¬ 
sects, they cease to affect it, and it, after a few years, recovers. 
Whether in such instances the insects perish for want of due 
nourishment, or whether they migrate to other trees, I am unable 
to say, though I incline to the opinion that the former is the case 
with the chief part of them. 
