62 



took them for scales from which males had clevelo2:)ed ; for this is 

 about the proportion of such scales usually met with in branches that 

 have not been medicated in any way. The old dead last year's scales 

 upon this piece of a branch, I did not think it necessary to count. 

 Hence, I infer that strong tobacco-water cannot kill the Bark-louse 

 at any period of its existence ; for if it has no efEect upon it when it is 

 in the tender larva state, a fortiori it will have no effect upon the ma- 

 tured or partly matured scale. 



That most accurate observer, Dr. Mygatt, arrived at similar re- 

 sults. "When I had ascertained," he says, "the hatching season, I 

 fondly hoped that the decoctions of quassia and tobacco, which I have 

 for several years used on the Plant-lice, (Aphides,) would also de- 

 stroy the young Bark-lice (Coccids;) but in that I was doomed to 

 be sadly disappointed on trial." {Trans. 111. State Agr. Soc. 1., p. 

 516.) 



Statement 2d. — On June 12th, 1867, I prepared a solution of 

 common saleratus, which, as soda has been very much cheaper than 

 potash ever since the mode of obtaining it from common salt was dis- 

 covered, was, in all probability, nothing but purified soda. It was 

 mixed in the proportion of one part, by measurement, of saleratus to 

 fifty parts of water. This I applied, precisely in the same way as 

 the tobacco-water in the preceding statement, to another branch, 

 prepared and labeled in a similar manner. Repeatedly, as the sum- 

 mer progressed, I examined this branch, and the young Bark-lice on 

 it seemed to be growing as nicely as on the rest of the tree. The 

 results, on cutting off, October 30th, a piece of the same size and 

 length, and similarly situated, as compared with that used in the 

 preceding experiment, were almost precisely the same. For I found 

 201 matured scales containing plump, healthy eggs, and nine that I 

 took to be male scales, though possibly some or all of them might have 

 been young larvae killed by the soda-wash. I did not count the old, 

 dead last year's scales, or those of the current year which were in- 

 fested or gutted by Mites; but I estimated that they were in all about 

 200 in number. From this experiment I concluded that a solution 

 of soda will not kill the Bark-lice even in the larva state; and I draw 

 the same inference as to the effect of alkaline solutions upon the 

 matured Bark-louse, that I have already drawn in the tobacco-water 

 experiment. 



The proportion of soda used was nearly that recommended in the 

 Horticulturist of March, 1867, namely, "one pound of potash to six 

 gallons of water;" for, as every druggist knows, a pint of such sub- 

 stances as soda is nearly the equivalent of a pound. All accounts 



