Author: Moriuti, 1972
Adult: 11-15 mm wingspan; forewings predominantly grey, marked towards the apex with leaden grey; and each with a dark pre-tornal marking and a dark grey basal patch, strigulated with white scales mixed with leaden scales; hindwings grey.
Larva: 9-12 mm long; head brown, abdomen usually pale greyish brown; pinacula and anal comb almost concolorous with the integument and comparatively indistinct.
Pupa: 5.5-8.5 mm long; golden brown, with outline of wing cases darker than abdomen. Cremaster absent.
Spilonota eremitana adult
External characters: 11-15 mm wingspan. Head and antenna grey; palpus dark grey, pale-speckled, the inner side being much paler; thorax grey, tips of scales pale grey, forming an obscure irroration; legs pale grey, pale-speckled, the mid tibia and tarsus being dark grey; abdomen grey. Forewing with termen a little oblique, straight and rounded at tornus; basal patch occupying nearly 2/5 of wing, dark grey, mixed or striated with whitish or leaden scales, and limited by a well-marked broad stria, sometimes its outer margin being obtusely angulated above fold; beyond this, wing predominantly grey, rather irregularly strigulated with white or whitish scales mixed with leaden scales; five dark grey streaks from costa between middle and before apex, and interstices between them whitish, the first streak being largest, reaching about 3/7 across wing, the anterior three tending to be confluent apically and sometimes forming an obscure costal patch marked with two whitish strigulae, and the fourth shortest and sometimes reduced to merely a costal dot; an irregularly shaped, weakly inwardly curved dark grey streak from just before apex of costa to about middle of termen; a distinct elongate-triangular dark grey pre-tornal marking; ocellus enclosed by obscure leaden streaks reaching about 3/4 across wing, sometimes confluent beneath, the outer streak being mixed with whitish scales, and the space between streaks filled with dark grey; cilia grey, with some scales tipped with white, the basal line being leaden-grey. Hindwing grey; cilia pale grey, with a darker subbasal line (Moriuti, 1972).
male genitalia S. eremitana
Genitalia: Uncus greatly reduced. Socius erect, short, subtriangular. Gnathos free and weak. Valva elongate, narrow, and curved; cucullus armed with a strong spine; neck very narrow. Aedeagus short; supporting arm of anellus very stout; cornuti composed of a cluster of 7-9 slender, elongate, spines which are easily shed. The genitalia provide no diagnostic characters to separate the males of this species of those of Spilonota ocellana.
External characters: Similar to male.
female genitalia S. eremitana
sterigma in S. eremitana
Genitalia: Papilla analis flattened, with numerous hairs; anterior portion narrow and weakly bending inwards. Sterigma fused with seventh abdominal sternite, more or less trapeziform, caudal margin straight, slightly concave or evenly convex. Ostial opening oval; ductus bursae well-sclerotized, except for a short membranous posterior portion; corpus bursae round, with a pair of short, curved, pointed signa, which are equal in size.
This species overwinters in the larval stage, and begins to feed in early spring.
Larix leptolepis, Larix dahurica var. japonica, Larix dahurica var. olgensis, Larix decidua.
Spilonota eremitana is an important pest of larch. Trees are completely defoliated when outbreaks occur.
Japan: Hokkaido, Honshu; Korea. This species is distributed practically throughout the range of its host-plant.
Pteromalus semotus (Walker) (Pteromalidae) (hyperparasite)