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[ 299 ] 
of the second brood, sometimes with the eggs of the Bark-louse 
upon which they have subsisted all consumed, and sometimes with 
a few remaining ; and in this state they undoubtedly pass the win¬ 
ter. This second brood must appear in the winged form early 
enough next summer to deposit the eggs from which the first 
brood of next year will proceed. 
The drawing made for the American Entomologist having been 
inaccurate, and the engraving imperfect, Mr. Biley kindly con¬ 
sented, at my request, to have a new engraving prepared, and the 
figure here given is a copy of the improved engraving. 
From this general destruction of the Bark-louse, it would seem 
that its virtual if not total extermination must be near at hand. 
Yet it would be imprudent to permit ourselves to come to this 
conviction with too much haste or certainty, since it is a truth 
with which we have become painfully familiar, that noxious in¬ 
sects have their periods both of increase and decrease, and that 
some species, of which the Chinch-bug is a notorious example, 
have returned with renewed life and profusion after years of ap¬ 
parent extermination. One of the ways in which this is brought 
about, I conceive to be this: the numbers of a certain species hav¬ 
ing become greatly reduced by the operation of its natural ene¬ 
mies, parasitic and others, these, in their turn, being deprived of 
their appropriate nutriment, also become reduced in like propor¬ 
tion. The remnant of the former species, being, we may pre¬ 
sume, naturally prolific, take a new lease of life and rapidly mul¬ 
tiply again in all their former profusion. Judging from known 
facts and experiences, it is reasonable to suppose that such ebb and 
flow in the prevalence of particular species, are ever taking place 
in the multitudinous world of insects. Such reflections have for¬ 
cibly occurred to my mind, as I have watched the parasitic Chal- 
cis-fly of the Bark-louse, coursing busily over the branches, amidst 
the dry and empty scales, in search of some suitable pabulum in 
which to deposit the germs of her future progeny. Another cir¬ 
cumstance which gives rise to some apprehension is, that these in¬ 
sects, within the last few years, have been found farther south 
than it has been heretofore supposed that they could subsist. I 
have received, this year, infested twigs from Mr. A. C. Hammond, 
of Warsaw, as far south as the northern border of Missouri. And 
I was informed at the horticultural meeting at Mr. Flagg’s, near 
Alton, on the sixth of October, that the Oyster-shell Bark-louse 
