46 
FIRST ANNUAL REPORT OF THE 
species of adult Mites, may be merely the two sexes or two different stages of one and 
the same species ; or very possibly, as is common in several families of insects, species 
of Mites, which are perfectly distinct in the adult state, may be undistinguishable in the 
larva state. 
I have only to add, by way of caution to the reader who may desire to verify the 
above new and very curious facts, that these young Mites, being so nearly of the same 
size, shape and color as the eggs of the Bark-louse among which they are found, and 
being also exceedingly dull and inactive in their movements, are not very easily recog¬ 
nizable. By long and attentive watching, however, and by trying several scales one 
after the other, a leg or two will at last be perceived, even under a common pocket 
magnifier, lazily flopping about; and even when the legs cannot be seen, a good lens 
will often discover the transverse suture across the body of the young Mite, which of 
course is not to be seen in the unliatched egg of the Bark-louse. It will be found that 
the shrunken eggs recently preyed upon by the Mite are of a yellowish color ; while the 
empty egg-shells (from which the young lice have hatched out,) that are constantly 
met with under old last year’s scales, are at first, not of a yellowish, but of a trans¬ 
parent white color. It is therefore among such shrunken eggs as are yellowish, not 
among such as are white, that these Cannibal Mites are to be looked for. So strongly, 
again, do these young Mites resemble the young Bark-lice when the latter are first 
hatched out, that even so practised an observer as Dr. Fitch evidently mistook the one 
for the other. For he says that the young Bark-lice of this species mostly hatch out 
about May 26th, but that so early as May 12th he found some still under the scale with 
“three pairs of legs, two placed anteriorly, the other posteriorly and distant.” (New 
York Reports , I. pp. 36-7.) As the legs of all young Bark-lice are equidistant or very 
nearly so, and those of all young six-legged Mites, so far as I know, precisely in accord¬ 
ance with the above description, these must clearly have been, not young Bark-lice, as 
the Doctor supposed, but young Mites. But even out of the errors, to which we are all 
of us subject, we may sometimes deduce useful and important truths. For Dr. Fitch’s 
error proves to us, that Mites must prey upon Bark-louse eggs, not only in Illinois, but 
also in New York. 
And now, after this protracted and tedious description of the Natural History of this 
mischievous insect, which has been made necessary by the prevalent errors and miscon¬ 
ceptions on the subject — let us approach the great practical question, “How are we to 
get rid of this pest?” It is with considerable reluctance that I enter upon this ques¬ 
tion, because I have in operation along train of experiments upon this important point, 
which are not yet finally concluded. I should much prefer, therefore, to wait till I can 
treat the matter as a whole at some future day, instead of taking it up piecemeal now. 
Still, as the conclusions at which I have already arrived seem to be of great practical 
moment, imperfect and fragmentary as they may be, I will lay them before the reader. 
They may be briefly stated thus : — 
1st. Strong tobacco-water has no effect whatever upon these Bark-lice, no matter at 
what time of the year it may be applied. 
2d. Strong alkaline washes have no effect whatever upon these Bark-lice, no matter 
at what time of the year they may be applied. 
3d. A strong solution of soap will kill almost every one of these Bark-lice that it 
touches shortly after they hatch out; but has no effect whatever upon the perfected scale. 
4th. Petroleum, or kerosene, or probably any oily or fatty substance, will kill every 
Bark-louse, eggs and all, that it actually touches at any time of the year. And there 
