DOUGLAS FIR PITCH MOTH. 21 



will emerge. 3 generations, those of the issues of 1913, 1914, and 1915, 

 may be located and destroyed at one time. However, no matter how 

 close the examination, a few infested pitch tubes will always escape 

 notice. It is therefore advisable that the same area be scouted 

 several times in the course of each season. After an area is once 

 cleared it should not be a difficult task to keep the insect in check and 

 much the less so if control projects cover big sections. 1 



Destruction of the larva is the only remedy that can be used to 

 reduce an infestation. When the infested pitch tube is located, it 

 should be separated from the tree, the thus exposed larva killed, and 

 to insure cleaner healing the ragged edges of the wound should be 

 smoothed with a knife or small ax, after which they should be painted 

 with creosote or a similar preparation, to prevent reinfestation by 

 insects or fungi. The enlarging of the wound by the smoothing of 

 its edges will also leave a pitch blister in the tissues, but the ultimate 

 result will not be nearly as disastrous as from the untreated sesiid 

 wound, since a clean healing from the inside obviates much of the 

 chance of its producing a circular seam. Freshly vacated wounds 

 might be treated the same way with profit. 



SUMMARY AND CONCLUSIONS. 



That the financial loss caused by Sesia novaroensis in Douglas, fir 

 product is great and represents a greater leak in profits to manu- 

 facturers than any other avoidable item is evident. 



That the depreciation for which this age is taxed can be eliminated 

 for the benefit of posterity at an expense so low that it is but a 

 fraction of that which the damage represents seems to be sufficiently 

 demonstrated by the results of the investigations and experiments. 



The manufacturer will always bear the greater extent of the loss, 

 and the manufacturing interests should inaugurate the elimination of 

 the insect by putting into effect a policy of paying better prices for 

 timber where it is clear of pitch seams and reducing the price com- 

 mensurately for materia] where logs are defective to an appreciable 

 extent, instead of paying a uniform amount of so much per thousand 

 i'eet in ;i I r >e;i | i i y. without c< n isi ( I era I ion of existing conditions. This 

 would create among owners of forest lauds a stimulus to produce clear 

 timber, free of pitch -earns, by a little attention annually, and even 

 if the immediate desire should be merely the obliteration of the 

 evidence on young trees by which the defect in the merchantable 

 material is determined, for the purpose of deceiving the lumber 

 cruisers, it would nevertheless produce (In- desired end. 



' i ndcr "Habitat" :■ n<i "Ho I Trees and Character of injury" is suggested where i<> 

 look for Infi ted tree , 



