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 hody stout, cylin- 

 drical 5 declivity of elytra oblique, scarcely flattened ; funicle of an- 

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



(V 



Fig. 217.— c, mine, with eggs, of Xyleborus ccelatue. 

 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 



Crypturgua atomus Le Conte. 



(Larva, Plate xxiv ; figs. 4, 5, 5a, 56 ; 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 li^'^ 

 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 

 profusion 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 



