60 . 



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 ]\Iites resemble the young Bark-lice when the latter are 

 first hatched out, that even so practised an observer as Dr. Fitch evi- 

 dently mistook the one for the other. For he says that the young 

 Bark-lice of this sjiecies mostly hatch out about May 26th, but that 

 so early as May 12th he found some still under the scale with "three 

 jjairs of legs, two placed anteriorly, the other posteriorly and distant." 

 {iVew Fork Reports, 1. 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 accordance 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 u|X)n 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 misconceptions 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 question, because I have in operation a long train of experiments 

 upon this important point, which are not yet finally concluded. E 

 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 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 tliey hatch out; but has no effect 

 whatever upon the perfected scale. 



4th. Petroleum, or kerosene, or probably any oily or fatty sub- 

 stance, will kill every Bark-louse, eggs and all, that it actually touches 

 at any time of the year. And there is pretty good evidence, that such 

 substances, if spread thinly over a great part of the surface of a tree, 

 and even if spread over its entire surface, are not perceptibly injuri- 

 ous to it, or at all events not invariably so. 



