INSECTS INJURIOUS TO CONIFERS. 



169 



not later than the middle of June and then carted away, and 

 the bark stripped and burned before the beetles have emerged, it 

 will serve to greatly diminish the numbers of those present. For 

 this special purpose traps may be established, which consist of 

 standing trees ringed about February ; after the beetles have 

 entered these, and are egg-laying and breeding in the bark, 

 they are cut down, and the bark is destroyed, as mentioned above, 

 before the larvse hatch out. Great care must be taken to see 

 that such bark is destroyed by the proper time, or the whole 

 result will be to increase the number of beetles present in the 

 forest. All stumps and dead wood left in sikc should be barked ; 

 and sickly trees should be cleared away before they h^.ve actually 

 become a prey to the larvae, unless they are to be used as tree- 

 traps. Much labour has been expended in clearing up the 

 blown-down shoots from the ground and in searching the 

 trees for those branches which contain holes. Neither plan is 

 commendable. The blown- down shoots are almost invariably 

 empty, and if the latter very troublesome method be adopted, 

 and the shoots are picked off and collected into a receptacle, it 

 will be found, when they are carried ofi to be burned, that the 

 beetles, if originally present, have all escaped. 



Other species of bark-beetles like those of the genus Hylastes, 

 which sometimes attack the roots of young trees — Tomicus 

 sex-dentatus,acuminatus, Laricis, chalcograijlms , and hidentatus, 

 all of which may occasionally prove troublesome — are to be 

 treated in the same way by the clearing out of brood-material, 

 and, if necessary, by the establishment of tree-traps." 



It' is to be noted that Myelopliilus imiijjerda never breeds in 

 the shoots where it feeds, and certain cases recorded where it is 

 supposed to have done so are due to a confusion between its larvsB 

 and those of Betinia, or of certain other beetles {Ernobius, &c.). 



A peculiar form of injury is that caused by the sucking of 

 the two kinds of Chermes — the Spruce-gall aphis, C. AbietiSj and 

 the Larch-aphis, G. Laricis. These insects, near neighbours of 

 the Phylloxera, have recently attracted much attention owing to 

 the peculiarities of their life-history, which have been investi- 

 gated by Blochmann, Dreyfus, Cholodovsky, Low, and Eckstein. 

 A resume of all the recent papers on the subject would be 

 beyond the scope of the present article, and, indeed, all the 

 results are by no means certain, and a brisk controversy has 



