D 



2 



IMPORTANT NORTH AMERICAN FOREST INSECTS 1.1 



THE HEMLOCK BARK MAGGOT 



Cheilosia alaskensis Hunter 



The hemlock bark maggot in the northern Eocky Mountain and 

 Pacific coast regions causes defects in western hemlock known as 

 " black check." The injury is caused by the larvae working in the 

 growing tissue of the tree. Similar defects in fir, spruce, and pine 

 are caused by related species (7). 



INSECTS AFFECTING FOREST PRODUCTS 



AMBROSIA BEETLES OR PINHOLE BORERS 



A number of species of beetles included in the genera Corthylus, 

 Gnathotrichus, Pterocyclon, Xyleborus, and Platypus are important 

 because of the injury they do to fire-scarred trees, green logs, and 

 green lumber. These insects, while working in the wood, not only 

 make holes but also introduce wood-staining fungi. In some locali- 

 ties a considerable quantity of wood otherwise sound and useful is 

 discarded because by the work of these beetles it is rendered unfit 

 for certain special uses (39, 40, 62). 



THE COLUMBIAN TIMBER BEETLE 



Corthylus columbianus Hopk. 



The Columbian timber beetle attacks living white oak, chestnut, 

 and yellow poplar, entering directly through sound bark. In some 

 localities from 15 to 25 per cent of the white oak lumber may be 

 affected, and where tight barrel staves are being manufactured whole 

 trees are discarded because of injury by this insect. The wood may 

 still be used for such purposes as base for veneer and for the in- 

 visible parts of various structures, as its strength is little impaired 

 (39,40,62). 



THE OAK TIMBER WORM 



Eupsalis minuta Drury 



The oak timber worm, entering through wounds, attacks the wood 

 of living trees and also frequently causes much damage to green logs 

 and produces defects in the lumber. It occurs throughout the eastern 

 part of the United States (39, 40, 62). 



THE CHESTNUT TIMBER WORM 



(Lymexylon) Melitt omnia sericeum Harris 



The chestnut timber worm attacks the wood of living chestnut. 

 Entering through a wound, it bores deeply into the center of the tree. 

 In the recent past, when chestnut was a more abundant forest tree, 

 this insect presented a serious problem, as from 75 to 90 per cent of 

 all the chestnut timber produced was defective (39, 40, 62). 



THE SAPWOOD TIMBER WORM 



Hylecoetus lugubris Say 



The sapwood timber worm attacks dying trees and green saw logs 

 of basswood, buckeye, chestnut, black walnut, cottonwood, yellow 

 poplar, and birch, causing considerable damage. Often a 5 to 10 per 

 cent loss occurs in logs on which the bark has been left (40, 62). 



