Some Insects Injurious to Forestry. 



By B. W. Adkin, F.S.I., F.E.S.— 7?mr/ Mai/ 22wl, 1919. 



Our President, when addressing us last winter, emplaasized the 

 importance of economic Entomology, and referred to its influence 

 on Forestry. His address caused me to think that a short paper 

 upon the subject I have chosen might be welcome to the members 

 of our society. I propose to say a few words upon Forestry before 

 dealing with certain of the insects which are injurious thereto. 



Forestry is an extensive science. One of its most important 

 branches is Silviculture, which may be interpreted as the culti- 

 vation of crops of trees with the object of profit. Silviculture may 

 be compared with agriculture, or the growing of farm crops for 

 profit, but, in my opinion, difficult as is the science of agriculture, 

 that of Silviculture is even more difficult ; for whereas an agricul- 

 turist may sow and reap a crop in one year, so that in an average 

 life he is able to study the results of perhaps fifty crops of the 

 same species of plant which he has sown, the silviculturist will be 

 lucky if he sees the result of a single crop which he has raised 

 from seed, for most of our trees take at least 60 or 70 years before 

 they reach maturity. Again, most of our common farm crops were 

 grown by the Anglo-Saxons, and have been grown continuously m 

 Britain ever since ; whereas most of the woodland crops which are 

 expected to prove most successful from a financial standpoint, con- 

 sist of trees which have been introduced into Britain but recently. 

 Further, the method of growing crops of trees in high forest 

 without underwood is comparatively new, so that there is but little 

 experience to go upon, while our insular conditions dift'er con- 

 siderably from those which prevail in continental regions, so that 

 experience gained upon the continent should be applied here only 

 with great caution. 



Silviculture is likely to be a far more important industry in 

 Britain than it has been in the past. The war has proved the 

 necessity of a large stock of growing timber to the welfare of the 

 nation, and the demands upon such stock as there was have been 

 met with difficulty. Many millions of cubic feet of timber have 

 been required, and the coniferous trees have been the chief 

 nece^^ity ; their destruction has enabled our mines to be worked, 

 and v.,.-it'T^ lantities of timber have been exported for the use of our 

 armies in the field. In the past about 95 per cent, of our home- 

 grown timber has been produced by private enterprise, without 

 state assistance, and usually at a heavy financial loss ; in the 



