MASSACHUSETTS WOODLANDS. 17 



The forestry methods of control consist of what we here term 

 moth thinnings. The moths themselves carry on these thinnings 

 in a crude way if left to ravage undisturbed. They will kill off most 

 of the " non-resistant " trees, together with many " resistant " ones, 

 it is true; but after many years, if undisturbed, the forest will grow 

 up almost wholly " resistant." Moth thinnings will prevent the 

 large waste which this natural method would entail, and also will 

 hasten the regeneration of the forest and save many " resistant " 

 trees which would not be killed unless mixed with the " non-re- 

 sistant " species. Thus these thinnings, like other kinds of thin- 

 nings, are for the purpose of saving and encouraging the growth 

 of the forest as a whole by sacrificing some of its unnecessary or 

 dangerous individuals. 



KINDS OF THINNINGS. 



Moth thinnings may be classified under four different heads 

 which are more or less distinct. 



1. Cuttings made solely for the Purpose of aiding in Direct 

 Methods of Moth Control. These are not real thinnings. They 

 usually consist of merely taking out the underbrush and a few dead 

 or undesirable trees. They have been carried on for years in prac- 

 tically all park and ornamental woodland where large sums of 

 money were to be spent in spraying the trees or painting the egg- 

 clusters. They are based on the principle that cuttings of this 

 character will greatly lessen the cost and increase the effectiveness 

 of the other work. 



2. Cuttings which are made for the Purpose of leaving the Wood- 

 land wholly " Resistant." Not over 5 to 10 per cent, of " non- 

 resistant" trees are left after a thinning of this sort; the brush 

 may or may not be cut, according to its character, and the expecta- 

 tion is that no further measures of moth control will be necessary. 

 These are moth thinnings of the extreme type. In stands which 

 have a good percentage of resistant growth they are real thinnings 

 and leave a fair forest cover. In stands almost wholly non-resistant 

 they practically amount to clear cutting, and should always be fol- 

 lowed by reforestation. 



3. Thinnings which are a Compromise between the Two Pre- 

 ceding Kinds. In the cutting all possible non-resistant trees are 

 removed, but not enough to seriously break the forest cover, and it 

 is expected that further measures of moth control, as spraying, will 

 be utilized when necessary. One purpose of this type of cutting 



