THE RELATION OF INSECT LOSSES TO SUSTAINED 



FOREST YIELD 



By W. J. Pearce 



Forest Examiner, U. S. Forest Service 



It is the purpose of this paper to present the insect problem from 

 the broader standpoint of its relation to forest management, rather 

 than the narrower one of a special protection problem. We must view 

 this whole subject of insects and their work in the same relation that 

 we view our other forest activities, such as timber sales, fire, grazing, 

 etc., in their ultimate relation to the perpetuation and improvement of 

 the forest. It is believed that in the past the subject of insects has 

 not received the attention of foresters in this country to the degree that 

 it should have, largely because it has been considered as lying within 

 the province of entomology rather than forestry, and secondly, because 

 lack of funds has made extensive and sustained efforts at control 

 impossible. Loses from insects are more insiduous than losses from 

 fire, and the destruction of a few trees here and there throughout the 

 stand, while in the aggregate amounting to a large loss, are apt to 

 pass unnoticed until they have assumed spectacular proportions. We 

 have in the past rarely, if ever, made any effort to control infestations 

 in the endemic state, but have usually waited until they have assumed 

 alarming proportions. It seems to me that this is an illogical procedure 

 and that a corollary in our fire problem would be to allow small fires 

 to go unfought until they had enlarged to vast conflagrations. These 

 remarks are not intended as a criticism of policy, as it is realized that 

 the only funds which have been available in the past have been obtained 

 through sacrifice of other activities. It is felt, however, that as the 

 administration of our timber resources becomes more intense, the 

 insect problem must receive more study and attention. 



In a subject of such large proportions, it is necessary to confine the 

 discussion to some particular phase or problem, and I have therefore 

 undertaken to review the situation as it exists in our stands of western 

 yellow pine. Not only is it our most important problem from the stand- 

 point of insect control, but it is also the problem of other administrative 

 units throughout its wide range, from Arizona and New Mexico to 

 406 



