Stigmella continuella (Stainton, 1856)
Diagnosis. See S. lemniscella above.
Male. Wingspan: 4.8-5.2 mm. Head: frontal tuft yellowish orange; collar pale yellow; scape yellowish white; antenna half length of forewing, bronzy brown. Forewing: area proximal to fascia greenish bronze shading into dark purplish brown at fascia; fascia shining silver to pale gold; distal to fascia dark purplish brown; terminal cilia dark brown shading into silvery grey at tips; underside of forewing purplish fuscous. Hindwing: grey, proximal half with a few slightly darker and larger scales; cilia pale grey. Abdomen fuscous with small yellowish anal tufts. Female. Wingspan: 5.0-5.3 mm. Antenna slightly shorter than in male. Abdomen fuscous, without anal tufts; ovipositor protruding. Male genitalia. Vinculum with anterior margin deeply emarginate. Uncus relatively large. Gnathos with short, broad horizontal bar and prominent, parallel horns. Valva with apical process on inner lobe slender and pointed. Transtilla with moderately long transverse bar and pointed sublateral processes. Aedeagus bottle-shaped; vesica with numerous spines; distal, weakly sclerotized spines obtuse and broadly triangular. Manica distinctly spined. Female genitalia. See group diagnosis; cannot be separated from those of S. lemniscella.
Host plants: Betula spp., including B. nana. Egg: on underside. Larva: yellowish, but appears green when in the mine. Mine : a long gallery mine, starting with a series of close- set convolutions, which turns brown; this is followed by a long gallery, often almost straight along a vein; mine almost completely filled with dark green frass. The mines are difficult to find because of the green larva (when in mine) and green frass which completely fill the mine. Vacated mines turn brown and are easily seen. Cocoon: brown.
In Denmark from NEJ, SZ and NEZ. From southern Sweden up to Vg. Not in Norway. In southern Finland up to Sb and Kb. - England, northern, central and eastern Europe. Probably also in the eastern Palaearctic (mines are known from China).
Voltinism: one generation per year in Scandinavia: mine during late July and August. Two generations in England and central Europe.
Description based on Johansson and Nielsen (1990)