THE STATE ENTOMOLOGIST. 119 



the next spring. Many rows of trees — mostly one year grafted — had 

 been left in the ground, however, and on examining these, I found 

 that wherever the previous year the lice had been numerous enough 

 to cover and deform the whole root, there that root had invariably 

 rotted. In many instances all trace of the knots and deformities 

 which the lice cause, had disappeared, while, in some few instances 

 they were yet traceable. In every case where rot had ensued the 

 lice had entirely left, so that not a trace of them could be found. 

 From these, and subsequent observations made during the summer, I 

 conclude that the rot does not ensue till the roots have been com- 

 pletely deformed by the lice, and while on a young tree a colony of 

 lice will multiply sufficiently to entirely cover it in a single season, 

 and thus cause it to rot the next year; on larger trees they may be at 

 work for years before this result is accomplished. This rot from root- 

 lice may, I think, be distinguished from both the other kinds by its 

 being more porous and soft, approximating the brown mould of a rot- 

 ting log. The unusual swellings and knots caused by the lice, though 

 hard originally, seem to loose their substance, and very frequently 

 the finer roots, and almost always the fibrous roots waste entirely 

 away. 



The diagnosis of either of the first two kinds of rot must remain 

 hidden, until our knowledge of these impalpable funguses shall have 

 become more thorough, and until then no remedy can be suggested ; 

 but with the last kind, having traced it to its true cause, the means of 

 prevention are at hand, and I will now give the history and descrip- 

 tion of the Apple-root Plant-louse for the most part as it appeared in 

 the American Entomologist for January, 1869 : 



For the last twenty years a Wooly Plant-louse has been known 

 to infest the roots of the apple-tree, causing thereon swellings and 

 deformations of almost every possible shape, and, when very numer- 

 ous, killing the tree. In the more northerly parts of the Northern 

 States this insect is comparatively rare, but in southerly latitudes it is 

 exceedingly destructive in apple orchards. According to Dr. Hull, "it 

 is one of the worst enemies against which our apple-trees have to 

 contend, and is much more common in our region than is generally 

 supposed." {Agr. Rep, Mo., Append., p. 451.) As long ago as 1818, 

 Mr. Fulton, of Chester county, Pennsylvania, found this root-louse and 

 the knotty swellings produced by it to be so abundant on nursery- 

 trees in his neighborhood, that thousands of young trees had to be 

 thrown away, and it became difficult to supply ihe market.) Down- 

 ing's Horticulturist, III, p. 391.) And in August, 1S58, M. L. Dunlap 

 (Rural) stated in the Chicago Tribune, that in an orchard near Alton 

 "the Wooly Aphis infests the roots in immense numbers, and by suck- 

 ing up the sap destroys the trees, which in its effect has much the ap- 

 pearance of dry rot." 



Although this insect usually confines itself to the roots of the tree, 

 yet a few may occasionally be found on the suckers that spring up 



