ILLUSTRATIONS. 



PLATE. 



Page. 



PLATE XXXIX. Fig. 1. Character of larval mines of oak-destroying bark- 

 borer in inner surface of bark. Fig. 2. Larval mines of 

 destructive bark-borer in surface of wood of dying cotton- 

 wood tree 320 



TEXT FIGURES. 



FIG. 27. Work of the hickory bark-beetle on surface of wood beneath the bark. 315 



28. Complete brood galleries of the hickory bark-beetle in surface of 



wood 316 



29. Exit holes* in bark of hickory tree from which broods of the hick- 



ory bark-beetle have emerged 317 



30. Brood galleries of the oak bark-beetle 318 



31. Brood galleries of the cherry bark-beetle, showing character of pri- 



mary galleries and larval mines _ 319 



32. Work of the birch bark-beetle 320 



33. Brood galleries of the ash bark-beetle in surface of ash wood 321 



34. Mines of a destructive bark-borer 322 



35. Pinholes in oak work of the oak timber-worm 323 



36. Wormholes in chestnut work of the chestnut timber-worm 324 



37. Wormholes in red oak work of the oak carpenter worm 324 



38. Work of the Columbian timber-beetle black holes and t( grease 



spots" in white oak 325 



39. Work of the Columbian timber-beetle " steam boats" in quartered 



or split white oak 326 



40. Work of the Columbian timber- beetle in tulip wood ' ' calico poplar ' ' . 326 



41. Work of Columbian timber-beetle end of log showing evidence of 



serious damage, and how the brood galleries made in the sapwood 



are covered by subsequent growths of wood 327 



42. Work of Columbian timber-beetle in sapwood of living tree 328 



43. Brood gallery of Columbian timber- beetle in sapwood of white oak. . 328 



IV 



