85 



DD The punctures of the striae shallow and usually small; the pale 

 band of the pronotum usually transverse and basal. 



bivittatum Kirby. Page 85. 

 CC Interspace 2 very narrow on the declivity and impunctate. 



D The pronotum with a caudal, pale, transverse band extending 



to the side margins ; the declivital interspaces 1 and 3 distinctly 



granulate; the male pronotum broadly, strongly emarginate 



in front as viewed from above. borealis Sw. Page 85. 



DD The pronotum and elytra without pale bands but with an 



obscure, smoky, reddish median area; interspaces 1 and 3 with 



granules nearly obsolete. 



E The striae feebly impressed on the declivity, with the 2nd 



interspace only feebly sulcate; the interstrial punctures 



rather coarse. rufitarsis Ky. Page 85. 



EE. The striae strongly impressed on the declivity, with the 



2nd interspace deeply sulcate; the interstrial punctures 



small. ponderosae Sw. Page 86. 



Trypodendron retusus Lee; Am. Ent. Soc. Trans. 2: 158, 1868 (Xyloterus). 

 Host trees. — Poplars. 



Distribution. — Abundant throughout Canada east of the Rockies, 

 in dying trees; apparently less common in British Columbia. (PI. 14, fig, 4). 



Trypodendron betulae Sw.; Can. Ent. 216, 1911. 

 Host trees. — Birches. 



Distribution. — Ontario, Quebec, and probably in the Maritime Pro- 

 vinces. 



Trypodendron cavifrons Mannh.; Bull. Mosc. 297, 1843 (Bostrichus).^ 



Apparently distinct from bivittatum, but presenting confusing variations. 

 Host trees. — Spruce, Pine, Giant Arborvitse, Birch, Western Alder. 

 Distribution. — The coast and southern interior of British Columbia 

 and southwards. 



Trypodendron bivittatum Kirby; Fauna BoreaHs Am., 4: 192, 1837 (Apate). 



Length, 3 mm.; width, 1-2 mm.; black with antennae, legs, a band 

 on the median part of the caudal border of the pronotum, and two longitud- 

 inal stripes on the elytra yellowish brown. The common species throughout 

 eastern Canada. 



Host trees. — Spruce, Pine, Arbor Vitae, Larch, Hemlock and Balsam. 



Distribution. — Eastern Canada from the Atlantic coast to northern 

 Alberta. 



An important variation occurs in the Rockies of northern Alberta 

 in white spruce. The colour is dark piceous to nearly black with the paler 

 markings smoky-yellowish and often indistinct. 



Trypodendron borealis Sw.; Can. Dept. Agric, Ent. Br., Bull. 14: 21, 1917. 

 Closely alhed to bivittatum, but distinct by the characters given in 

 the key. 



Host trees. — White Spruce. 



Distribution. — Northern Saskatchewan and northern Alberta. 



Trypodendron rufitarsis Kirby; Fauna Borealis Am. 4: 193, 1837 (Apate); 

 Bethune, Can. Ent., 4: 152, 1872.. 



Similar in size and shape to T. bivittatum; distinguished by colour 

 characters, the coarsely and rather sparsely granulate front, the shallow 

 declivital sulcus and impunctate 2nd interspace, the nearly obsolete 



