Archive image from page 24 of Defects in timber caused by. Defects in timber caused by insects defectsintimberc1490snyd Year: 1927 DEFECTS IN TIMBER CAUSED BY INSECTS 23 Under present methods of lumbering, such imported logs usually are infested by pinhole-boring beetles of many species, which attack the logs after they are cut, and continue to live in them for several months and in some cases a year or more. If such logs are shipped into another country with a similar climate, the insects may survive and attack logs of native timber; if, on the other hand, logs are exported to a much colder
Archive image from page 24 of Defects in timber caused by. Defects in timber caused by insects defectsintimberc1490snyd Year: 1927 DEFECTS IN TIMBER CAUSED BY INSECTS 23 Under present methods of lumbering, such imported logs usually are infested by pinhole-boring beetles of many species, which attack the logs after they are cut, and continue to live in them for several months and in some cases a year or more. If such logs are shipped into another country with a similar climate, the insects may survive and attack logs of native timber; if, on the other hand, logs are exported to a much colder or hotter country, the insects will rarely, if ever, become established in the country of import. There is, therefore, some danger of introducing destructive species through the commercial interchange of timber in the form of logs. Fig. 25.—Wormholes caused by ' sawyers ' (Monochamus spp.) in pine. A and B, wormholes in southern yellow pine ; C, wormholes in white pine For example, many insect species are widely distributed over tropical America that do not occur in tropical Africa, Asia, Australasia, and the Pacific islands. Tropical Australia, the Philippine Islands, and tropical Japan doubtless have a considerable number of the same species of pinhole borers. One country may have a few that do not occur in the others. DEFECTS CLASSED AS GRUB HOLES OR WORMHOLES Grub holes are medium to large, circular, oval, or irregular holes from three-eighths to 1 inch in diameter, in both sapwood and heart-
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