18 IMPROVEMENT THINNINGS IN 



is to enable the owner to maintain a forest cover at the least pos- 

 sible expense, with no unnecessary trees to take care of, and with 

 the largest possible proportion of resistant trees. The real purpose 

 of these thinnings should be to make it the first step in a gradual 

 elimination of all non-resistant trees, and the remaking of the forest 

 into one of a resistant character without too great a disturbance of 

 the forest conditions during the process. Natural reproduction or 

 underplanting of desirable species should follow the cutting. 



4. Damage Cuttings. To a greater or lesser extent in all wood- 

 land where the moths have been present for a number of years there 

 are moth-damaged trees which have to be removed when a- thinning 

 is made. However, under this heading it is intended to include 

 only cuttings made for the main purpose of marketing the dead 

 and damaged trees before they become too much decayed to be 

 merchantable. Of course this sort of a cutting has no effect in 

 controlling the moths. The wood cut from dead trees is not usually 

 as valuable as that cut from live ones, and also it costs more to cut 

 it; so damage cuttings are only profitable in better quality growth 

 near a good market. Resistant thinnings should be made where 

 possible before serious infestation, to prevent the necessity of 

 damage cuttings. 



ADVANTAGES AND DISADVANTAGES OF THINNINGS AS A METHOD OF 



MOTH CONTROL. 



The great advantage of thinning is in its small cost. The direct 

 methods of moth control are a net expense and are liable to have 

 to be repeated year after year. In most woodland the annual cost 

 of spraying or of a thorough creosoting is greater than the value of 

 the wood which that woodland will produce in a year. Therefore 

 it is cheaper for the owner, unless the area has a considerable value 

 other than for the wood it grows, to cut down all his trees and 

 sell them than to try direct methods of control. This fact is well 

 known, and is the reason why in recent years little attempt has 

 been made to stop the moths in woodland unless it was mainly 

 used for park or pleasure purposes, or in case of a light infestation, 

 to keep it from spreading. 



Moth thinnings will pay for themselves, or come very near doing 

 so, as will be seen from figures of actual operations which are given 

 later. The product in cord wood, ties, piles, logs, etc., will, in 

 almost every growth which is at least fair, pay for the work done, 

 and in many cases will yield a profit. 



