Fifth report of the United States Entomological Commission, being a revised and enlarged edition of Bulletin no7, on insects injurious to forest and shade trees . larger portion of them reside in or immediately beneath the barkof different trees, and are currently termed bark-beetles. But thisdesignation is inappropriatefor another portion of them which dwell inthe interior of the wood, and there excavate their galleries. The nametimber-beetles appears to be the most appropriate for these. Anotherpoint in which, from the observations of M. Perris, these two groupsappear to differ in
Fifth report of the United States Entomological Commission, being a revised and enlarged edition of Bulletin no7, on insects injurious to forest and shade trees . larger portion of them reside in or immediately beneath the barkof different trees, and are currently termed bark-beetles. But thisdesignation is inappropriatefor another portion of them which dwell inthe interior of the wood, and there excavate their galleries. The nametimber-beetles appears to be the most appropriate for these. Anotherpoint in which, from the observations of M. Perris, these two groupsappear to differ in a remarkable manner is the relative numbers of thetwo sexes. With the bark-beetles there are commonly several males incompany with but one female, and the former appear to perform thechief part of the labor in the excavation of their galleries. With thetimber-beetles, on the other hand, the females are much the most numer-ous, and probably mine their galleries without any assistance from theother sex. M. Perris states of one of the species that upwards of fiftyfemales were met with in the burrows they had excavated without asingle male being found THE PINE TIMBER-BEETLE. 719 It is the habit of these timber-beetles to penetrate the tree in astraight line, passing inwards through the bark and into the sap-woodto a depth of from half an inch to 2 inches, andthen abruptly turning they extend their burrowin another straight line parallel with the outersurface and at right angles with the fibers of thewood, for a length of 2 to 6 inches. The only in-stance in which the burrow of the species nowunder consideration has come under my noticewas recently in a billet of stove wood, which un-fortunately did not contain the extreme end ofthe gallery. The annexed cut* is an exact repre-sentation of this burrow, in which a live and adead beetle were found, both of them females, andthe only specimens of this species which havecome under my observation. The transverse bur- materanus. Ma
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