54 
FIRST ANNUAL REPORT OF THE 
at first and afterwards blood-brown, without any powdery bloom ; and consequently, 
from their extreme minuteness and from their being very sluggish in their movements, 
they can scarcely be seen on the bark with the naked eye. On June 12th, I observed 
some — which I identified as belonging to this species because they were still under the 
parent scale — to be of a pale blood-brown color, without any powdery bloom ; they 
had the same longitudinal ridge and transverse grooves as the other species. The inex¬ 
perienced eye, if it noticed them at all at this date on the bark, would be almost sure to 
confound them with the natural pores of the bark, which at first sight they greatly 
resemble. 
2d. I have been unable to trace satisfactorily the history of Harris’s Bark-louse from 
June to September, because the Oyster-shell species had invaded every one of my trees, 
that had been originally occupied exclusively by the native species ; so that it w r as 
difficult to distinguish one kind of larva from the other kind. I could only ascertain 
one point clearly, namely, that the matured scale of the female, which is milk-white, 
is not formed till about the middle of September, and that the eggs are not developed 
under that scale till the end of September or some time in October; whereas, as we 
have seen, in the other species the matured female scale, which is the color of the bark, 
is formed, and the eggs fully developed, by the middle of August. Certainly, from the 
middle of June to about the middle of September, the females must remain of the same 
dark inconspicuous color as before ; for the white scales, which are so conspicuous, 
appear all of a sudden on the bark in the middle of September. Dr. Houghton, of 
Philadelphia, as well as myself, noticed this fact. He has 20,000 pear-trees badly 
afflicted by this pest. “ Up to Sept. 15th,” he says, “ I flattered myself that there was 
not a living insect of this description in my orchard. I thought that the winter of 
1865-6 had been so cold, that it had killed them all. But lo ! on the 20th of September 
there were millions upon millions of Bark-lice on my pear-trees.” (Practical Entomolo¬ 
gist , II., p. 30.) 
3d. On Sept. 17th, or some weeks before any eggs were developed, I lifted up over 10 
perfected female scales. Under each of them, and entirely separated from the scale 
itself, I found a legless, beakless, fleshy, elongate-oval Bark-louse, about 2>£ times as 
long as wide, with its body divided into pretty distinct segments, the 3 first of which, 
and in a less degree the 2 next, were very much hunched laterally. The color was 
yellow, blood-red, or pink, and the length about 0.03 inch. One of these I saw move very 
distinctly, showing that it was really alive. 
4th. The scale of this species is of a much more delicate- consistence than that of the 
Imported Bark-louse, and it rarely remains unbroken on the bark after the eggs hatch 
out, but is generally either more or less mutilated or entirely removed by the weather. 
The empty egg-shells are white., as in the other species. 
5th. The empty scales, which are supposed by Harris to have produced males, may 
be found in considerable numbers in the autumn loosely attached to the bark, or some 
of them scarcely attached at all. Towards the spring they are generally most of them 
washed off by the weather. As these never occur on trees infested exclusively by the 
Oyster-shell species, they cannot belong to that species ; and I therefore, by the method 
of exhaustion, infer them to belong to Harris’s Bark-louse. They are oblong-oval in 
shape, of a pure white color, with the usual yellowish “larval scale” attached at one 
end, the remaining portion having its sides perfectly parallel, and being as wide as the 
“ larval scale ” is long, and in length from 2 to 2% times as long as the “ larval scale.” 
There is no “medial scale ” behind the ‘‘larval scale,” as there always is in the ma- 
