236 ON THE CORSICAN FIR. 



deficiency and thus maintain a proper balance. The only 

 mode of prevention must be to endeavour to give the young 

 plants some shelter {e.g., reserving a few of the parent trees per 

 acre), if natural reproduction be employed, or planting three to 

 four year old larches or birches (better, however, larch) here and 

 there to shed a beneficial, by no means deep, shadow around, if 

 sowing or planting operations be carried out. 



Snow and hoarfrost likewise do not cause so much breakage 

 as in the case of the Scotch fir, for though the leaves being longer 

 afford a better resting-place for the snowllakes and dew, yet the 

 twigs and branches are more elastic. 



For a long time it was considered that the cockchafer {Mcla- 

 lontha vulgaris) was the only insect that did much damage to 

 this tree (by gnawing the bark from the roots of young plants 

 when a grub), but more recent and accurate observation has 

 proved this opinion to be incorrect. Tlie localities in which 

 insects will most frequently be found making attacks must be 

 such as are unfavourable to the growth of the tree, or where it is 

 cultivated along with, or in proximity to, species of conifers, most 

 commonly destroyed by insects, e.g., Scotch and spruce firs. A 

 large supply of resin must act as a safeguard, so that forests on 

 rich, deep, and fresh soil, or on the cool, moist northern, north- 

 eastern, and north-western slopes will be more exposed, seeing 

 that under such circumstances less resinous fluid is produced. 



The names of the insects already observed on the Corsican fir 

 may here be briefly enumerated, without, however, going into 

 details as regards nature and amount of damage usually done, 

 &c. 



On the root, stem, or branches — Hylohius pi7ii, Fissodes 

 notatus, 3Iclalontha vulgaris, Bostrichus hidens, B. lariciSy 

 Hylesimis jpiniperda. 



On buds and young shoots — Hylesinus jjini'pcrda, Tortrix 

 Buoliana, T. rcsinana, T. turionana. 



On leaves — Lijyaris monacha, Lojjhgriis pini. Zijjaris dispar^ 

 Gastropaclia pini, Nodiia piniperda, and Geometra piniaria will 

 also, in all probability, soon be added to this list. 



Great damao;e is seldom done to old trees : occurring in 

 general before the 20th year, and not unfrequently causing 

 serious apprehension for the future of the young forest. 



It may not be without interest to state the quantity of 

 timber per acre yielded by the Corsican fir, and the average 

 periodical increase of gTowth. 



