Diagnosis. Somewhat similar to S. auromarginella but easily separable by the copper-brown proximal half of forewing and broad bluish silvery fasciae in lediella. The male genitalia differ from all European Stigmella in having the narrow valvae with very long, inwardly curved distal process and aedeagus with relatively few and short cornuti. The female genitalia of lediella are similar to those of S. splendidissimella but differ in having longer and narrower vestibulum and dense cover of pectinations on corpus bursae. The illustrations of the male genitalia of two Rhododendron- feeding species from South-eastern USSR: S. magica Puplesis, 1985c and S. rhododendri Puplesis, 1985c show only minor differences from lediella. External features and female genitalia of the Japanese species S. sesplicata Kemperman & Wilkinson, 1985 (on Rhododendron) show only very slight differences from lediella.
Male. Wingspan: 5.0-5.7 mm. Head: frontal tuft ochreous, vertex orange; collar dark brown; scape pale golden; antenna three-fifths length of forewing. Thorax shining copper brown. Forewing: area proximal to fascia shining copper-brown, slightly darker before medial fascia; with two fasciae, one medial, broad and oblique, and one short and narrow along distal margin, both shining brightly bluish to greenish silver; distal to medial fascia dark brown to almost black; terminal cilia dark grey-brown, slightly paler at tips. Hindwing: yellowish grey with bronze reflections; cilia pale grey-brown. Abdomen dark grey-brown, more or less suffused with copper and purple. Female. Wingspan: 5.2-6.0 mm. Antenna approximately half length of forewing. Fascia usually broader. Otherwise similar to male.
Male genitalia. Vinculum short and broad with distinct medial emargination. Uncus relatively small, subtriangular with broad, square medial emargination and small or indistinct paramedial notches. Gnathos with lateral arms and anterior processes forming rectangular plate; horns strong, forming a V. Valva with narrow inner lobe and very long, inwardly curved distal process. Transtilla with long transverse bar and long sublateral processes. Juxta present. Aedeagus as long as genital capsule, with 20-25 cornuti: 12-15 in proximal half, 4-5 cornuti distally, and a cluster of 6-8 needlelike spines. Female genitalia. Vestibulum long and narrow. Corpus bursae large, entirely covered with longitudinal rows of very minute folds and transverse rows of pectinations. Accessory sac approximately half length of corpus, without spines and pectinations. Ductus spermathecae as long as corpus, posterior half with dense cover of spines. Apophyses posteriores distinctly longer than anteriores.
Host plants: Ledum palustre. Egg: on upper surface of leaf. Larva: yellow. Mine : a conspicuous, gradually widening gallery, usually following the margin of the leaf. Frass deposited as a black, frequently interrupted central line. Cocoon: yellowish brown.
Not in Denmark and Norway. In Sweden from Sk. to Nb. Widely distributed in Finland up to Ks. - Eastern C. Europe: Estland, Poland, Czechoslovakia and Austria.
Voltinism: in Scandinavia univoltine. Mines from mid-September to early October. In Poland supposed to be bivoltine (Schleich, 1867) but this has not been confirmed by breeding. Wet localities; bogs and damp woods.
Description based on Johansson and Nielsen (1990)