152 



THE SCOLYTID BEETLES. 



mens, and in the collection of the Museum of Comparative Zoology 

 by over 50 specimens. 



Pupa. In addition to the generic, divisional, and subdivisional 

 characters, the front and middle femora are armed each with a 

 minute apical spine; abdominal tergites 1 to 6 with moderately 

 small pleural spines; 1 is without dorsal spines, but with distinct 

 lateral ones; 2 to 6 have small dorsal and lateral spines, the former 

 increasing in size to 6, and all have dark tips; 7 and 8 are unarmed; 

 9 has the usual stout pleural spine. Pupal type labeled "Hopk. 

 U.S. 2824."- 



FIG. 9l.Dendroctonus valens: Egg galleries and larval chamber. A , Incomplete egg galleries with boring 

 dust removed; B, normal gallery; C, advanced stage of work; a, entrance burrow; b, basal section; 

 c, ventilating burrow^ d, egg nest with eggs; e, boring dust; /, subsequent or inner galleries; g, larvae 

 at work; h, pupal cell in boring dust mixed with resin. (Original.) 



The usual variation prevails in the number and arrangement of 

 minor spines and between the young and older examples. 



The character which in general serves to distinguish the pupa of 

 this species from the preceding is found in the darker tips to the 

 body spines. 



Larva (text fig. 39 and PL VIII, fig. 23). In addition to the ge- 

 neric, divisional, and subdivisional characters, front of head with pos- 

 terior angle, median area not elevated but transversely rugose, except 

 near apex, where it is smooth; epistoma flat, opaque, smooth, with 

 straight anterior margin ; clypeus broad, prominent, convex, with faint 

 median longitudinal line, sides rounded, apex broadly emarginate; 



