Diagnosis. S. obliquella is very similar to S. salicis and S. myrtillella. In salicis, the colour of the forewing is more brownish and the fascia is frequently constricted or broken in middle, sometimes obliterated. The male genitalia differ in the shape of gnathos and valva; the female genitalia in shorter apophyses, shorter anal tufts and spined ductus spermathecae in obliquella. See also diagnosis of S. myrtillella.
Male. Wingspan: 4.6-5.7 mm. Head: frontal tuft yellowish orange to brownish orange; collar and scape white to yellowish white; antenna half length of forewing or slightly longer. Thorax dark grey to fuscous. Forewing: area proximal to fascia dark grey-brown, coarsely scaled; fascia more or less oblique, pale yellow, wider at dorsum and sometimes extending along dorsum towards base, giving fascia a bent appearance; distal to fascia brownish black; terminal cilia pale yellow beyond a distinct line of dark tipped scales, grey at tornus. Hindwing and cilia grey. Abdomen blackish with small grey-brown anal tufts. Female. Wingspan: 5.0-6.0 mm, frequently darker with more contrasting wing pattern. Abdomen grey with short yellowish grey anal tufts; ovipositor not protruding. Male genitalia. Vinculum with shallow to moderately deep anterior emargination. Uncus small, almost square with small medial incision and shallow paramedial notches. Gnathos with parallel, close set horns, usually fused at base. Valva relatively short, divided into long and strong distal process and inner lobe. Transtilla with short, blunt sublateral processes. Aedeagus distinctly shorter than genital capsule with 6-7 relatively short unilaterally sclerotized cornuti and 2-3 long, slender spines; sometimes with small additional spines at base. Female genitalia. Corpus bursae with broad band of sharply dentate chitin plates, surrounded by pectinations; posterior part narrow. Ductus spermathecae with small internal spines. Apophyses anteriores and posteriores equally long; anal tufts approximately half length of apophyses. Ovipositor not or only slightly protruding, tip blunt.
Host plants: seems to prefer Salix species with smooth and narrow leaves: fragilis, pentandra, alba, babylonica and viminalis, occasionally on other Salix species. Egg: on either side of leaf, usually close to midrib or margin. Larva: yellow. Mine : a gradually widening gallery; first half either contorted or following a rib or leaf margin, second half a wide gallery or elongate blotch; frass black, almost completely filling first half of mine, but broken at 1 to 2 millimetres intervals and irregularly dispersed in blotch. Cocoon: brown to red-brown.
Eastern Denmark, in Sweden from Sk. to T.Lpm.; in Norway only from ø; in Finland from Al to ObN. - Central Europe to eastern Poland and Hungary, northern Italy and England.
Voltinism: bivoltine, larvae in late June and early July, and from late September to mid-October. In Sweden, the summer generation seems to be scarce or absent.
Description based on Johansson and Nielsen (1990)