SPRUCE BARK-BEETLES. 



825 



different species, and indeed it is probable that from variations in age^ 

 and size, too many species of these bark-borers have been described. 



Leconte states that the genus Xyleborus has "the body stout, cylin- 

 drical ; declivity of elytra oblique, scarcely flattened ; funicle of an- 

 tennae with four distinct joints j tibiae finely serrate on the discal half 



CL 



Fig. 211.— c, mine, •with eggs, of Xyleborus ccelatus. 

 Gissler del. 



278. — Xyleborus ccelatus, 

 J. B. Smith and Miss 

 Sullivan del. 



of their length and rounded at tip." X. ccelatus ranges from Canada to 

 Texas and California. In this species " the declivities of the elytra at 

 the end of the body are with two prominent tubercles, and some smaller 

 marginal ones ; elytra strongly punctured in rows : interspaces with 

 rows of distant punctures." (Identified by Dr. Horn.) See also p. 709. 



3. The least spruce bark-borer 



Crypturgus atomus Le Conte. 



(Larva, Plate xxiv; figs. 4, 5, 5a, 5&; pupa 5c.) 



Order Coleoptera; family Scolytid^. 



This minute bark-borer, though often occurring in white-pine bark, 

 must not be confounded with Pityophthorus puberulus of the white pine 

 (p. 715), as its burrow is very different. The present species is l^™"* 

 long, and f ""^ in diameter. The mine consists of a short sinuous pri- 

 mary gallery about one-half inch long, which gives off at intervals about 

 ten short secondary galleries from each side, but they are not made in 

 the same plane, next to the sap-wood, as in P. puberulus, but penetrate 

 only the bark itself in all directions, so that no regular pattern is formed. 

 The beetle is extremely numerous, a great many mines being densely 

 situated within a square inch of surface. They were observed in great 

 I)rofusion in the larva, pupa, and beetle states at Brunswick, Me., dur- 

 ing August; in standing dead trees as well as spruce stumps; also in 

 white-pine stumps. Many of our observations on this and the fore- 

 going species, as well as the Rhagium, were made by the side of Maquoit 



