. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. THE GENUS DENDROCTONUS. 63 cies, all of which extend their galleries from the entrance in a trans- verse or sublongitudinal and tortuous course through the inner bark (fig. 19). Those of different pairs of beetles frequently cross each other so that the many primary galleries, independent of the larval mines, serve to com- pletely girdle the tree and kill the bark. Thus these winding galleries cause a much more rapid death of the bark and foliage than do the straight longitudinal gal- leries, like those of the sp
. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. THE GENUS DENDROCTONUS. 63 cies, all of which extend their galleries from the entrance in a trans- verse or sublongitudinal and tortuous course through the inner bark (fig. 19). Those of different pairs of beetles frequently cross each other so that the many primary galleries, independent of the larval mines, serve to com- pletely girdle the tree and kill the bark. Thus these winding galleries cause a much more rapid death of the bark and foliage than do the straight longitudinal gal- leries, like those of the spruce beetles and the Black Hills beetle. The trees are killed by the girdling effect of the winding primary galler- ies in the bark of the middle portion of the trunk, which, it has been demonstrated, is the most vital part, or at least has less power of resisting injuries than the lower portion and base. Instead of the leaves of the trees re- maining green until the next season, as they do on trees infested by the spruce beetle and the Black Hills beetle, all except those on the trees attacked late in the sea- son commence to fade in a few weeks after the trees become Fig. 25.—White pine timber killed by southern pine beetle Condition in October, 1894, of trees which died in 1891 and 1893. (Original, from photograph.) ECONOMIC FEATURES. This species may be considered as one of the most dangerous enemies of the pine forests of the Southern States. It devastated the pine forests over large areas in West Virginia and Virginia in 1891 and 1892, and the extensive dying of pine timber in the Southern States during. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States. Bureau of Entomology. Washington : G. P. O.
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