Key to the species ol Scolytus in Canada and Alaska
Abdominal sternites unarmed in both sexes, sternite 2 not concave; elytral bases not strongly scabrous in either sex One or more abdominal sternites carinate, tuberculate, or armed with several teeth or spines in male at least (sometimes reduced in subscaber)i sternite 2 either concave or convex; elytral bases usually scabrous in female
Ventral segments gradually ascending to elytra, sternite 2 oblique, not vertical (Figs. 5, 6)ain deciiiuous trbes . . .
3
Ventral segments abruptly ascending to elvtra. sternite 2 vertical, concave or convex; in coniferous and deciduous trees
3.
Smaller, less than 2.5 mm long; elytra with short hairs over entire surface; pronotal punctures large, deep, cloie; usually in fruit trees, Western and Eastern Canada (fig.S)....... ....rugulosusRatzeburg Larger, over 3.0 mm long; elytra glabrous on disk; pronotal punctures very fine, widely separated, shallow; various deciduous hosts, Eastern Canada (F ie.6)..
.zali
(Beschtein)
Elytral surface, frons, and ventral surface densely pubescent, especially in male; male ' frons strongly flattened, strongly sculptur6dl in Celtis spp.. Eastern Canada ...zratrcrsSaY (Fig.7)...:...
Elytral surface, frons, and ventral surface not densely pubescent in either '
sex;
male frons not as strongly flattened and not as stronglysculptured; in coniferous -(fig. . . . tsugae (Swaine) S) trees, Western Canada
5.
6.
Sternite 2, in male at least, deeply concave, with anterior margin strongly extended, and usually carinate in medlan line; female with sternite 2 similar or convex with a more weakly elevated margin and carina reduced or lacking
6
Sternite 2 in both sexes vertical, not concave, armed with a median tubercle, spine, or carina, anterior margin weakly produced
ll
Sternite 2 of male very deeply concave. weakly carinate: posterior margin of sternite 4 with three long.'acuti ipines. margin ofiternite 5 with one acuteipine (-fig.S)t male frons strongly flatt'ened, denstly pubescent on lateral margins.; adults of
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Sternite 2 of male not as deeply concave; posterior margin ofsternites 4 and 5 unarmed; male frons not broadly fiattened, pribescence more generally distributed; smaller in size: in Western Canada
Anterior margin of sternite 2 of male distinctly thickened; sternite 2 of male lacking an elevaied, median carina or tubercle, surface faintly punctured, depressed in . . otegoni Blackman median portion; chiefly in Pseudotsuga spp. . . . Anterior margin of sternite 2 of male not esoeciallv thickened: sternite 2 of male bearing an elevated A bies spp.
8.
Sternite 2 of male bearing a strongly elevated median carina, which extends from the posterior margin to ihe centei'of the sternite, the carina more strongly elevated
it
its ventral aoex . .
Sternite 2
26
carina or tubercle, surface-variously punctured; chiefly in
of male bearins a somewhat obscure median carina or small tubercle ......
9
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