128 PROTECTION OF WOODLANDS. 



but also creating blanks in the canopy and the crops, that may be 

 unnecessary, and must be undesirable. 



In addition to these purely financial points of view, it must 

 not be overlooked that, as previously mentioned, sickly stems 

 afford only too attractive and favourable a breeding-place for 

 many kinds of noxious insects, and that attacks of Scolytidaz are 

 especially to be feared in crops which have already been much 

 injured and weakened in vigour by the devastations of caterpillars 

 among the foliage. Of course, where such may be feared to be the 

 case, 1 the clearance of sickly stems must be allowed to be of more 

 pressing necessity than the felling of trees that have already 

 succumbed to their injuries. 



Damage to, and disturbance of, the cambial layer by the larvae 

 of beetles and weevils generally results in the immediate death of 

 the stem, which is soon recognisable through the foliage rapidly 

 becoming brown and then falling off. It is more difficult to 

 decide about the extent to which damage has been done by cater- 

 pillars, for the question virtually raised as regards denudation of 

 the foliage to any great extent in conifers, is whether or not the 

 needles still adhering are sufficient to maintain the life of the tree 

 and if there is any reasonable hope of the terminal and axial buds 

 attaining development in the following spring. 2 



Among the signs which betoken the approaching death of stems 

 may be included the appearance of all sorts of insects under th( 

 bark ; flabby, soft, drooping, withered-like buds ; needles of the Pirn 

 devoured down into the sheaths ; scaling off of the bark ; am 

 brownish or bluish patches showing on the inner bark and sa] 

 wood. It will be advisable to retard felling operations whei 

 it happens that the damage takes place in autumn, so that th< 

 buds have a chance of developing, or when no total denudation 

 the foliage has taken place, or when the crops damaged are youngam 

 growing on soil of good quality, where there is always a much 

 better hope of their recovery than on inferior soils and situations. 



1 In the Ebersbeger Park, near Munich, the chief beetles which followed the Spruce- 

 moth in 1891 were the Harz rostral beetle (Pissodes hercyniae), the four-eyed bark- 

 beetle (Hylesinus polygraphus), and the Spruce cervicorn (Callidium luridum). 

 (FwfePauly,qp. tit., p. 78). Trans. 



2 With regard to this point, it must be remarked that the recuperative power of 

 the Scots pine is much greater than that of the Spruce fir, the former being ulti- 

 mately able to recover although over 50 per cent, of its foliage be devoured. Trans. 



