119 



Ips dubius, n. sp. 



This species agrees closely with tridens and engelmanni in the characters 

 of the pronotum and elytra, although the punctures are usually rather 

 smaller and the striae less impressed; the front of the head is entirely dis- 

 tinct, evenly convex and coarsely, sparsely granulate, the epistoma slightly, 

 transversely impressed, the median line smooth towards the vertex, less 

 roughened than the sides, and shining cephalad to the epistomal impression. 

 It is to be separated from interruptus by the same character and by the 

 sparser elytral punctures; in interruptus the front is usually very densely, 

 finely granulate, and the elytral punctures small and close. Ten specimens 

 were dissected, representing variations; all were males. The forms here 

 discussed as tridens, engelmanni and dubius are taken in the same sticks 

 and even together in the same tunnels. This may be due, as is indicated 

 elsewhere, to the wandering of the late-feeding young adults, or it mp y be 

 that dubius is the male of engelmanni, or less probably of tridens. I. pilifrons 

 Sw. is closely allied to engelmanni, and has a somewhat similar frontal 

 structure; the form taken with pilifrons and described by the writer as 

 probably the male, differs from pilifrons exactly as dubius does from 

 engelmanni. Biologic studies must be depended upon to determine the 

 relations between these forms. For the sake of convenience dubius is 

 given a name; the other form may be referred to as pilifrons d" until its 

 status is settled. 



Type. — A male; Rogers Pass, B.C.; Picea engelmanni; 28-IX-15; 

 J.M.S., 2254. Type No. 111. 



Host trees. — Engelmann's Spruce, and possibly also White Spruce. 



Distribution. — Known to us from the Selkirks and Rockies between 

 Glacier, B.C., and Banff, Alta. 



Ips pilifrons Sw.; Can. Ent., 46: 353, 1912. 



Abundantly distinct by the characters given in the key. The form 

 described as probably the male was taken with the type, but may be the 

 male of another species; it differs only in having the front convex and 

 coarsely, densely granulate and moderately thickly clothed with long, 

 yellow hairs. Our specimens are mostly from the Cornell University 

 collection and are all from Colorado. 



Ips tridens Mannh.; Bull. Mosc, 357, 1852 (Bostrichus). 



The length varies from 3 • 8 mm. to 4 • 8 mm. ; with the upper part of the 

 front convex, shining, coarsely and deeply but not densely punctured, with 

 a wide, minutely punctured, transverse impression between the eyes, the 

 region between this impression and the epistomal margin occupied by an 

 enormous, transverse, elevated, subacute, finely granulate, nearly glabrous 

 mass, concave behind, oblique, impressed along the middle line, flattened 

 and minutely pubescent in front; the pronotum with the sides moderately, 

 arcuately narrowed on the sides, rather strongly narrowed in front of the 

 middle and narrowly rounded in front; moderately, deeply punctured 

 behind; the elytral striae usually distinctly though variably impressed, with 

 the strial punctures round, of medium size and deep, the declivity of the 

 male pini type, but with the third tooth rather small and usually hardly 

 capitate. The race in the Selkirks and Rockies has the pronotum usually 

 rather coarsely and closely punctured behind. A series from the Yoho 

 Valley, B.C., has the frontal elevation of the same shape but somewhat 

 smaller. Leconte's type is probably a Mannerheim specimen. 



Host trees. — Engelmann's Spruce, Sitka Spruce, and probably White 

 Spruce. 



Distribution. — Alaska; Inverness, B.C.; the Selkirks and Rockies of 

 central British Columbia between Glacier, B.C., and Banff, Alta. 



