. Defects in timber caused by insects. Wood; Forest insects. 28 BULLETIN 1490, U. S. DEPARTMENT OF AGRICULTURE heart wood of both hardwoods and softwoods, from which the powder will fall when moved or The interior is honeycombed by irregular burrows made by the larvae and when badly damaged is converted into a mass of closely packed material, which readily crumbles into fine flourlike powder or coarser pellets of excreted wood. This is held together by an outer thin shell and intervening fibers of soimd wood. These defects will be discussed in the order of the size of the holes cause
. Defects in timber caused by insects. Wood; Forest insects. 28 BULLETIN 1490, U. S. DEPARTMENT OF AGRICULTURE heart wood of both hardwoods and softwoods, from which the powder will fall when moved or The interior is honeycombed by irregular burrows made by the larvae and when badly damaged is converted into a mass of closely packed material, which readily crumbles into fine flourlike powder or coarser pellets of excreted wood. This is held together by an outer thin shell and intervening fibers of soimd wood. These defects will be discussed in the order of the size of the holes caused by the various types of insects. All powder-post damage can be prevented. POWDER POST CAUSED BY LYCTUS BEETLES The inj ury caused by Lyctus beetles is confined to the white- wood or sapwood of hardwoods ($4). It consists of small holes one-sixteenth to one- twelfth of an inch in diameter, with irregu- lar burrows filled with flourlike powder. Air- dry or kiln-dry sap- wood material, and sapwood which has been stored or piled in one place for two. three, or more years, especially second- growth ash, hickory, and oak, are princi- pally affected; but other hardwoods, such as walnut, maple, persim- mon, cherry, elm, poplar, and sycamore, are also damaged. Seasoned shipbuilding and airplane lumber and gunstock blanks, stored in large quantities, and finished stores, such as wheelbarrows, tent poles, oars, airplane parts, shovel and pick handles, and many other hardwood articles used in the military services are subject to serious damage by powder-post beetles. (Fig. 28.) Hickory, ash, and oak furniture, interior woodwork of buildings (fig. 29), and the woodwork of farming machinery and implement handles; ladder stock, such as rungs; vehicle stock, such as hubs, spokes, felloes, rims, singletrees, poles, and shafts: and cooperage stock (barrel-stave bolts) are also Fig. 30. -Powder-post defect in pine made by â peltatus Xyli â Insects which have this peculiar habit of r
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Keywords: ., bookcentury1900, bookdecade1920, bookpublisherwa, booksubjectwood
