10 



BARK AND WOOD BORING GRUBS. 



This class of enemies differs from the precedino- in the fact that the 

 parent beetles do not burrow into the wood or bark, but deposit their 

 eggs in the surface. The elongate, whitish, round-headed (Ceram- 

 bycid), flat-headed (Buprestid), or short, stout (Curculionid) grubs 

 hatching from these eggs cause injury by burrowing beneath the bark 

 or deep into the sapwood and heartwood of living, injured, and dead 

 trees, sawlogs, etc. Some of the species infest living trees, causing 

 serious injury or death. Others attack only dead and dying bark and 

 wood, but this injury often results in great loss from the so-called 

 worm-hole defects. 



BARK-WEEVILS. 



This class of insects includes species which injure and kill the central 

 shoots of pine and spruce, such injury often resulting in deformed 

 and worthless matured trees. Others attack the base of young trees 

 and apparently cause their death, or breed in the bark of injured and 

 dying standing trees, and logs and stumps of those recently felled. 



BARK AND WOOD BORING CATERPILLARS. 



This class includes the young of clear-winged, wasp-like moths, 

 which mine in the bark and wood of living trees, causing masses of 

 pitch to form over the wound. They often cause serious damage to 

 reproduction and plantations of conifers and other trees. 



INFESTING THE WOOD. 



AMBROSIA OR TIMBER BEETLES. 



This class of insects attack living, dead, and felled trees, sawlogs, 

 green lumber, and stave-bolts, often causing serious injury and loss 

 from the pin-hole and stained-wood defects caused by their brood 

 galleries. The galleries are excavated l)y the parent beetles in the 

 sound sapwood, sometimes extending into the heartwood, and the 

 young stages feed on a fungous growth which grows on the walls of 

 the galleries. 



TIMBER WORMS. 



This class of true wood-boring "worms," or grubs, are the larvas of 

 beetles of the families Lymexylidie and Brenthidse. They enter the 

 wood from eggs deposited in wounds in living trees, from which they 

 burrow deep into the heartwood. Generation after generation may 

 develop in the wood of a tree without affecting its life, but the wood 

 is rendered worthless for most purposes by the so-called worm-hole 

 and pin-hole defects resulting from their burrows. The same species 

 also breed in the wood of dying and dead standing trees, and in the 



