718 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 



main galleries cross each other, while iu another case two unite to 

 make a figure 8, but in such a case the secondary galleries do not 

 cross the main ones, and in examples where two main galleries run 

 parallel and somewhat near each other, they do not send secondary 

 galleries into the narrow interspaces between the two main galleries. 

 On submitting specimens of the beetle to Dr. Le Conte for identifica- 

 tion, he writes us that it is a species of Pityophthorus^ not described. Br. 

 Le Conte adds: "Blanchard writes that Hypophloeus tenuis depredates 

 on this species.'' (Le Conte afterwards identifies it as probably P. 

 puberulus.) 



44. Xyleborus imjyressits Eichhoff. 



Le Conte states that this species occurs in Greorgia under pine bark. 



45. Pine timber-beetle. 



Gnathotrichus materiarius (Fitcb). 



Order Coleoptera ; family Scolytidje. 



In the interior of the sap-wood, mining slender straight cylindrical burrows in a 

 transverse direction, parallel with the outer surface, from which very short straight 

 lateral galleries branch off at right angles above and below, a rather slender cylin- 

 drical black shining bark-beetle, 0.15 long, with pale dnll yellow legs and anteunse, 

 the forepart of its thorax and of its wing-covers tinged with reddish yellow ; the 

 thorax equaling two-thirds the length of the wing-covers with a small elevated 

 tubercle iu the middle, forward of which it is rough from minute elevated points : 

 the wing-covers with rows of minute punctures, their tips rounded, the upper part of 

 the declivitj' with a shallow longitudinal depression or groove aloug the suture, 

 forming a slight notch. 



" The insects belonging to the genus Tomiciis and kindred genera of the 

 same family by their habits divide themselves into two distinct groups. 

 The larger portion of them reside in or immediately beneath the bark 

 of different trees, and are currently termed bark-beetles. But this 

 designation is inappropriatefor another portion of them which dwell in 

 the interior of the wood, and there excavate their galleries. The name 

 timber-beetles appears to be the most appropriate for these. Another 

 point in which, from the observations of M. Perris, these two groups 

 appear to differ in a remarkable manner is the relative numbers of the 

 two sexes. With the bark-beetles there are commonly several males in 

 company with but one female, and the former appear to perform the 

 chief part of the labor in the excavation of their galleries. With the 

 timber-beetles, on the other hand, the females are much the most numer- 

 ous, and probably mine their galleries without any assistance from the 

 other sex. M. Perris states of one of the species that upwards of fifty 

 females were met with in the burrows they had excavated without a 

 single male being found there. 



