'^ INSECTS INJURIOUS TO CONIFERS. 



The immense importance of the destruction caused by these attacks 

 has given an impetus to the study of forest insects on the Continent, 

 and a not inconsiderable mass of literature has sprung up. In this 

 the foremost place must be given to the works of Katzeburg. 

 Besides Katzeburg and his pupils and successors in Germany, Ferris 

 in France, Lindeinan in Kussia, and Packard in the United States 

 have especially contributed to our knowledge of Conifer-feeding insects. 

 In Great Britain less has been done to advance our knowledge 

 of them, perhaps because owing to geographical position and 

 climate its insect population is comparatively small, and serious 

 damage fortunately rare. There are many papers scattered through 

 British journals of entomology and sylviculture on those six or 

 seven species of insects which have done serious injury to Conifers, 

 but there is a deficiency of information with regard to the less 

 important kinds. 



In the large number of insects feeding on these trees only a few 

 are of habitual importance, but exceptional abundance of a normally 

 unimportant species will bring about unexpected damage, This 

 sometimes occurs in Great Britain, and one may hear complaints 

 of damage which is not assignable to any of the regular destroyers, 

 but which cannot be identified in the absence of specimens. It is 

 about these casually destructive species that we require to know 

 more. 



The special liability of some Conifers (Finns, Picea, Abies, Larix) 

 to injury by insects, and the important character of such injury, are 

 due to the following facts : 



1. There is a large number of insects which attack them. 

 Kaltenbach enumerates 299 on the forest Conifers in Europe. This 

 number falls, indeed, far short of the 537 assigned to the Oak, but 

 neither list can be taken as strictly accurate. 



2. Every part of the tree is liable to energetic attacks from one 

 insect or another the roots, the bark of the trunk and branches, 

 the wood, needles, shoots, and lastly the cones, the seed-production of 

 which may be greatly lessened by insects feeding in their interior. 



3. A common form of injury, especially on the Continent, is 

 defoliation. Xow complete defoliation of a Conifer, other than the 

 Larch, usually means the death of the tree, because of the slowness 

 with which the injury is repaired. If an Oak is stripped, it grows 

 a new crop of leaves late in the year, provided that the defoliation 

 is sufficiently complete and sufficiently early ; but if a Spruce or Fine be 

 stripped and survive, not only are no further needles produced the 

 same year, but next year's growth may be delayed a month, and the 

 new needles are stunted and form the curious "bristle-needles" figured 

 by Ratzeburg. The tree will take four or five years to recover its 

 normal covering of needles, and with them its normal process of 

 growth ; so that during that period the total increment will only 

 equal, or may even be less than, that of a single ordinary season. 



