18 



resembles very closely. Its galleries are excavated in the sapwood of 

 perfectly healthy trees. After a short occupancy they are abandoned 

 by the beetles, and, being overgrown by successive annual layers, are 

 ultimately found in the heartwood. 



According to Professor Hopkins, successive generations of the bee- 

 tle make their galleries in the same tree, not materially affecting its 

 vitality, but doing serious injury to the quality of the timber by filling 

 it with defects. The galleries of this species fork once or twice soon 

 after entering the wood. Fig. 9 shows in horizontal section a gallery in 

 yellow poplar. The branches are straight and nearly parallel when the 

 sapwood has a thickness of several inches, but when the sapwood is 

 thin they diverge and curve more or less to avoid entering the heart- 

 wood. The larvse are raised in separate brood cells or cradles, which set 

 off from the main gallery at a considerable angle, as shown diagram- 

 matically in fig. 9. 



sj 



Fig. 9.— Galleries of Corthylus columbianus in Liriodendron, with diagram of brood cells (adapted 

 from drawings by A. D. Hopkins). 



The number of young raised in oak or beech does not exceed 10 or 

 12 to a colony. In colonies from yellow poplar (Liriodendron) their 

 number is somewhat greater. The mature beetles probably remain 

 over winter in the galleries. The following spring they issue forth and 

 make new galleries in the immediate vicinity of the old. The food fun- 

 gus of C. columbianus has not been examined. It leaves, however, an 

 intensely black stain which in soft wood extends with the grain several 

 feet upward and downward from the galleries. Of the geographical 

 distribution of this recently discovered beetle very little is known. All 

 our knowledge of its habits we owe to the studies made by Professor 

 Hopkins in West Virginia. He has also observed defects, attributed 

 to this species, in lumber from Michigan. A specimen of the beetle 

 was found by Mr. E. A. Schwarz on the shore at Fortress Monroe, Ya., 

 and a specimen in the cabinet of Mr. Ulke bears the label Massachu- 

 setts. From these indications it may be surmised that the species is as 

 widely distributed as C. punctatissimus. 



