Diagnosis. Very closely related to S. myrtillella and vimineticola. S. myrtillella differs from the variable salicis in having usually darker forewings with more distinct fascia and white cilia; vimineticola differs salicis from in having indistinct or absent fascia and more yellowish cilia. The male genitalia are exceedingly similar and somewhat variable, the only reliable differences seem to be the cluster of slender spines in the aedeagus: in salicis 4-8 of unequal length and almost straight, number of cornuti and spines 9-13; in vimineticola 4-8 of unequal length, the longest distinctly curved, number of cornuti and spines 11-14; in myrtillella 4-7 equally long, short and straight, number of spines and cornuti 7-10. The female genitalia of myrtillella differ from those of salicis by shorter, more curved apophyses and shorter anal tufts; those of vimineticola by sharply pointed ovipositor, long and strong apophyses and presence of distinct spines in ductus spermathecae. Also similar to S. obliquella, see diagnosis of that species.
Male. Wingspan: 4.9-6.6 mm. Head: frontal tuft pale ochreous to yellow or ferruginous; collar yellowish white to ochreous; scape white to pale yellow; antenna two thirds length of forewing, grey. Thorax dark grey-brown. Forewing: area proximal to fascia varying from yellowish brown to dark grey-brown, appearing more or less coarsely scaled; fascia yellowish white to yellow, oblique and constricted in middle; sometimes reduced into costal and dorsal spots, indistinct or absent; distal to fascia dark grey- brown to brownish black, coarsely scaled; terminal cilia white to pale yellow, strongly contrasting with distal part of forewing; pale grey at tornus. Hindwing: pale grey-brown; cilia similar. Abdomen dark grey with small grey anal tufts. Female. Wingspan: 4.8-6.2 mm. Antenna half length of forewing. Forewing usually darker with more distinct fascia than that of male. Abdomen dark grey; ovipositor protruding; anal tufts long, yellowish grey. Male genitalia. Vinculum with shallow to distinct anterior emargination. Uncus subtriangular with deep, square medial emargination; paramedial notches varying from distinct to absent. Gnathos with horizontal bar and anterior processes forming a rectangular plate; horns long, well separated at base, parallel to slightly diverging; lateral arms narrow. Valva almost parallel-sided, posteriorly rounded with two short and pointed, inwardly curved processes. Transtilla with moderately long to very short sublateral processes. Aedeagus slightly to distinctly shorter than genitalia capsule with 5 to 6 unilaterally sclerotized cornuti and a cluster of 4 to 8 slender spines of unequal length; spines almost straight. Number of cornuti and spines varying from 9 to 13. Female genitalia. Corpus bursae with sparse pectinations and a distinct band of dentate, scallop-shaped chitin plates. Ductus spermathecae without spines. Apophyses long, posteriores slightly shorter than anteriores. Anal tufts approximately half length of apophyses. Ovipositor protruding, tip blunt.
Host plants: Salix spp., seems to prefer rough-leaved sallows; rarely on Myrica gale. Egg: on underside of a leaf, usually close to a vein or leaf margin. Larva: yellow. Mine : variable; in small leaves often contorted with confluent windings forming a false blotch; in narrow leaves usually following leaf margin or ribs; first half of mine almost filled with frass; second half with frass deposited as a broad and irregular central line. Cocoon: pale brown.
Widely distributed and common all over Scandinavia and Finland, including the northernmost region: - C. Europe, Mediterranean and the British Isles.
Voltinism: in S. Scandinavia and C. Europe bivoltine; mines in July and from mid-September to mid-October. In N. Scandinavia univoltine with mines from late August to early September.
Description based on Johansson and Nielsen (1990)