IMPORTANT NORTH AMERICAN FOREST INSECTS y 



Prionoxystus and Goes. The borers attack living oak trees, mining 

 deeply into the sapwood and heartwood (18). 



THE ELM BOEEE 



Saperda tridentata Oliv. 



THE LINDEN BOREB 



Saperda vestita Say 



THE POPLAR BOKEB 



Saperda calcarata Say 



The larvae of the poplar borer riddle the heartwood of several 

 species of poplar, opening it to decay and making the trees subject to 

 windfall. It is widely distributed throughout the range of the host 

 plants. Several other species of this genus, among which Saperda 

 tridentata in elm and S. vestita in linden are important, are injurious 

 to living trees (18, 27, 38). 



THE WESTERN FLB BOREB 



Tetropium abietis Fall 



In the Pacific coast region the western fir borer occasionally kills 

 large numbers of true firs by mining beneath the bark. Trees weak- 

 ened by defoliation or fire are particularly susceptible to attack 



US)- 



THE WESTERN LARCH BARK BOREB 



Tetropium velutinum Lee. 



The western larch bark borer is occasionally a pest of considerable 

 importance in stands of western larch and hemlock in the Rocky 

 Mountain and Pacific coast regions of the United States. The larvae 

 mine in the inner bark (18. 68). 



THE CEDAR POLE BORER 



Track i/kele blondeli Mars. 



The larvae of the western cedar pole borer riddle the heart and 

 sapwood of living western red cedar, causing serious defects and 

 the consequent rejection of the damaged material for lumber, shin- 

 gles, and poles. This borer occurs in Oregon, Washington, and 

 California (9). 



THE PITCH MOTHS 



Dioryctria aoietella D. and S. 



Dioryctria xanthaenooarea Dyar 



Dioryctria ponderosae Dyar 



Dioryctria amatella Hulst 



The inner bark of the trunks, the new growth of the leaders, and 

 the cones, of pine, Douglas fir. spruce, and fir are often seriously 

 injured by the caterpillars of the pitch moths. Death of parts or 

 even the entire tree and the loss of seed of the infested cones fre- 

 quently follow the injury. These insects are important, but little 

 work has been done on them. 

 29679°— 30 2 



