INSECT INJURIES TO FOREST PRODUCTS. 



385 



body (figs. 43, <?, and 45, a). North American species vary in .size from 

 less than one-tenth to slightly more than two-tenths of an inch, while 

 some of the subtropical and tropical species attain a much larger size. 

 The diameter of the holes made by each species corresponds closely to 

 that of the body, and varies from about one-twentieth to one-sixteenth 

 of an inch for North American, and to one-eighth of an inch for the 

 tropical species. 



KOrXD-ITEADED BORERS. 



The character of the work of this class of wood and bark-boring* 

 grubs is shown in figure 46. The injuries consist of irregular flat- 

 tened or nearly round wormhole defects in the wood which sometimes 

 result in the destruction of the valuable parts of wood or bark material. 



FIG. 46. Work of round-headed and flat-headed borers in pine: a, work of round-headed borer, 

 's;i\\ yt.-r," Mniiohammns sp., natural size; 6, Eryates spiculatus; c, work of flat-headed borer, 

 Jitiitnafia. larva and adult; d, bark; e, sapwood; /, heartwood. (Original.) 



The sapwood and heartwood of recently felled trees, sawlogs, poles, 

 po^ts. mine props, pulpwood, and cord wood, also lumber or square 

 timber with bark on the edges, and construction timber in new and old 

 buildings, are injured by wormhole defects, while the valuable parts 

 of stored oak and hemlock tanbark and certain kinds of wood are con- 

 verted into worm dust. These injuries are caused by the young or 

 larvae of long-horned beetles. Those which infest the wood hatch 

 from eggs deposited in the outer bark of logs and like material, and 

 the minute grubs hatching therefrom bore into the inner bark, through 

 which they extend their irregular burrows for the purpose of obtain- 

 ing food from the sap and other nutritive material found in the plant 

 tissue. They continue to extend and enlarge their burrows as they 

 increase in size, until they are nearly or quite full grown. They then 

 enter the wood and continue their excavations deep into the sapwood 



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