_Columbian Timber-beetle_ One of the commonest wormhole defects in white oak, rock oak, beech, and tulip ("whitewood" or "yellow poplar") is one known to the lumber trade as grease spots, patch-worm, or black holes, Fig. 99, steam boats, Fig. 100, etc., caused by the Columbian timber beetle (_Corthylus columbianus Hopk_.) The characteristic feature of this wormhole defect, which will enable it to be readily recognized in oak and beech, is transverse series of two or more black holes about the size of the lead in an ordinary lead pencil, with a streak of stained wood extending with the grain two or three or more inches each side, as in Fig. 99. In quarter-sawed oak or split or sawed staves, a short longitudinal section of one of these black holes is seen attended by the stained streak on one side of a thick or curly growth or grain, Fig. 100. It is this form which is called "steamboats." In whitewood (yellow poplar) the black holes are attended by very long black, greenish, or bluish streaks, sometimes five or six feet long. When this is common in the lumber it is called "calico poplar." Fig. 101 represents the characteristic appearance of this defect greatly reduced. (Hopkins, _Agric. Yr. Bk._, 1903, p. 327.) [Illustration: Fig. 99. Work of the Columbian Timber Beetle: Black holes and "grease spots" in white oak. [_Agric. Year Book_, 1903, Fig. 38, p. 325.]] [Illustration: Fig. 100. Work of the Columbian Timber Beetle: "Steamboats" in quartered or Split white oak. [_Agric. Year Book_, 1903, Fig. 39, p. 326.]] [Illustration: Fig. 101. Work of the Columbian Timber Beetle in Tulip Wood, "Calico Poplar," [_Agric. Year Book_ 1903, Fig. 40, p. 326.]] _Carpenter bees._ The work of this class of woodboring bees is shown in Fig. 102. The injury consists of large augerlike tunnels in exposed, solid dry wood of buildings and other structures. It is most common in soft woods, such as pine, poplar, redwood and the like. (Hopkins, _Agric. Yr. Bk._, 1904, p. 390.) [Illustration: Fig. 102. Work of the Carpenter Bee, _Xylocopa orpifex_, in Redwood Lumber: _a_, entrance; _b_, galleries; _c_, cells; _d_, larva; _e_, adult. [_Agric. Year Book_, 1904, Fig. 53, p. 390.]] _Horn tails._ This is a class of borers which are the larvae of the so-called wood wasps. They may enter the exposed dead wood of wounds of living trees, but more commonly attack the wood of dead standing conifers and hard woods, in the sap-wood of which they excavate irregular burrows, which are packed with their borings. When the adults emerge they leave the surface perforated with numerous round holes. Water and fungi entering these holes cause a very rapid decay of the wood. (Hopkins, _Entom. Bull._ No. 48, p. 11.) The tunnels of these various wood pests are most frequently to be seen in chestnut, ash, hickory, oak, tulip, and cypress.