. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. THE BLACK HILLS BEETLE. 13 gallery is distinguished from that of the spruce-destroying beetle by its slender form and more evenly distributed side or brood mines. CHARACTERS OF THE INFESTED TREES (fIG. 4 AND PL. Il). Trees attacked by the Black Hills beetle between July and October will be indicated by the presence of pitch tubes, or sawdust borings, and upon removal of the bark the young broods will be found mining tln-ough the inner living layers, or the bark will be entirely killed on the main trunk; but the f
. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. THE BLACK HILLS BEETLE. 13 gallery is distinguished from that of the spruce-destroying beetle by its slender form and more evenly distributed side or brood mines. CHARACTERS OF THE INFESTED TREES (fIG. 4 AND PL. Il). Trees attacked by the Black Hills beetle between July and October will be indicated by the presence of pitch tubes, or sawdust borings, and upon removal of the bark the young broods will be found mining tln-ough the inner living layers, or the bark will be entirely killed on the main trunk; but the foliage will remain green, or will be but faintly faded until May and June of the following year, when the leaves on the lower branches will turn yellow and die. This condition will rapidly extend to the topmost leaves, so that by the time the broods of maturing beetles are ready to emerge the foliage is yel- lowish red to light reddish brown in color. This is the stage of death called "sorrel ; Later in the sum- mer and during the following winter, after all living ex- amples of the beetle have emerged, the foliage is dark red- dish brown, called "red ; This condition prevails during the second summer after attack; but by the third summer all, or nearly all, of the leaves have fallen, which gives the tops of the dead trees a blackish appearance, called "black ; Beginning with freshly attacked trees during the first summer, they are distinguished by the exudation of fresh wliitish or reddish pitch forming small masses or tubes on the bark of the main trunk or by the presence of fresh reddish sawdust-like borings lodged in the loose bark and around the base of the Fig. 3—Work of the Black Hills beetle, in inner bark of dead tree: o, primary galleries; 6, larval mines; c, pupal chambers; d, exit holes. Reduced about one-half. (Author's illustration.). Please note that these images are extracted from scanned page images that may
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