Diagnosis. S. sorbi is exceedingly similar to S. lapponica in external characters: lapponica normally has slightly more coarsely scaled forewings, a less distinct fascia, and the females have no anal tufts (see also S. lapponica). The male genitalia of sorbi are distinctive in their large size and the long vinculum. The female genitalia can be recognized by the combination of long apophyses, protruding ovipositor, absence of accessory sac and corpus bursae almost completely covered with pectinations.
Male. Wingspan: 6.5-7.5 mm. Head: frontal tuft and collar grey-brown to yellowish brown; scape white; antenna three-quarters length of forewing, dark grey. Thorax grey-brown. Forewing: area proximal to fascia dull grey-brown without metallic sheen; fascia diffuse, pale yellowish grey; distal to fascia grey brown, slightly darker than proximal part; terminal cilia pale grey-brown. Hindwing: pale grey; cilia similar. Abdomen dark grey, with small grey-brown tufts. Female. Wingspan: 6.0-7.0 mm. Frontal tuft and collar pale ochreous. Antenna slightly longer than half forewing length. Proximal part of forewing paler and fascia broader than in male. Abdomen with long pale grey anal tufts. Male genitalia. Vinculum large and elongate. Uncus large, with deep medial notch and small, sometimes indistinct, paramedial notches. Tegumen relatively long, as wide as uncus. Gnathos with moderately long horizontal bar and long, widely separated horns. Valva narrow with two relatively long apical processes. Transtilla with distinct sublateral processes. Aedeagus very long, with a large number of needle-like cornuti; close to tip a prominent subtriangular plate-shaped structure and 8-10 long, strong cornuti. Manica sparsely spined. Female genitalia. Corpus bursae ovoid, almost completely covered with pectinations. Accessory sac absent. Ductus spermathecae longer than corpus bursae. Apophyses long, posteriores and anteriores of subequal length; ovipositor protruding.
Host plants: Sorbus aucuparia, S. intermedia and closely related species, Cotoneaster spp., Malus spp. and Amelanchier spp. Egg: on the underside. Larva: transparent to very pale greenish, head pale brown. Mine : a very slender, sinuous gallery 15-20 mm long, abruptly widening into a blotch about 10 mm wide, sometimes engulfing the earlier gallery part of the mine. Frass densely packed in second half of gallery, scattered in centre of blotch. Frequently each leaf or leaflet with many confluent mines. Cocoon: brown.
In eastern Denmark including F, from almost all districts in Sweden, widespread in Norway and Finland to the Arctic Sea. - Ireland, Britain, central and eastern Europe, in particular in high altitudes.
Voltinism: one generation per year. Larva in second half of June. Adults in northern Scandinavia among the first moths to appear in early spring (often with S. lapponica); in southern Scandinavia later, in second half of May.
Description based on Johansson and Nielsen (1990)