154 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



insect-attacks, displayed even by responsible people, is often so 

 astounding that one has a right to expect that even the simplest 

 and best-known facts will have the charm of novelty for some- 

 body. 



The special liability of some Coniferje (Pinus, Picea, Abies, 

 Larix) to injury by insects, and the important character of such 

 injury, are due to the following facts : — 



1. There is a very 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. 

 Many species are omitted, especially from the former list, while 

 in the case of the Oak the number appears to be swelled by the 

 dragging in of species having little real connection with that tree.* 



In Eatzeburg's " Forst-Insekten " 95 species are tabulated as 

 injuring Conifers, while only 86 are referred to the Oak ; but 

 subsequent researches would increase both these figures. 



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. Now 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 by Tortrix viridana — an annual 

 occurrence in many English w^oods — or a Hawthorn by 

 Hyponomeuta padella, as in our London parks and gardens, the 

 tree generally grows a new crop of leaves late in the year, 

 provided that the defoliation is sufiiciently complete and 

 BufiQciently early ; but if a Spruce or Pine 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 Eatzeburg. 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 incre- 



* The list gives all insects occurring on the tree, whether injurious 

 or not. 



