Author: (Denis and Schiffermüller, 1775)
Species Overview:
Adult: 18-22 mm wingspan; forewings light grey to whitish, marked with reddish-brown and yellowish, often with an expanded costal blotch, or forewing; hindwings grey. A very variable species.
Larva: 14-16 mm long; head brownish green or light green, region of stemmata blackish; prothoracic plate light green, with a black lateral marking; abdomen light green, darker dorsally; pinacula shining, concolorous with integument; anal plate light green; anal comb present; thoracic legs light green.
Pupa: 8-10 mm long; light brown.
Taxonomic Description:
Male:
Acleris sparsana adults 1
Acleris sparsana adults 2
External characters: 18-22 mm wingspan. Labial palpus grey brown, cream-grey basally; head dark grey to brownish-grey; thorax brownish grey, abdomen greyish. Forewing not expanding terminally, relatively broad, costa strongly curved at base, almost straight posteriorly; apex delicately rounded; termen straight, oblique. Forewing variable:
- ground colour grey finely irrorate with whitish, markings obsolescent (indicated by ferruginous and pale ochreous striae, most apparent costally), with a few scattered raised black scales, including slight tufts near base of median fold, or
- forewing light grey to grey with a large triangular costal blotch and well-developed and conspicuous basal fascia.
Cilia light grey. Hindwing grey, paler basally (after Razowski, 1984; Bradley et al., 1973).
male genitalia A. sparsana
Genitalia: Tegumen broad, broadening subterminally, concave in middle of posterior edge; socii large, tapering terminally; tuba analis broad with small median plate before end ventrally; valva broad; sacculus strong, broad basally, concave before middle of ventral edge, then angulate, with broad spined termination; brachiola large. Aedeagus slender, bent beyond coecum penis; cornuti: two short spines and plate-shaped sclerite.
Female:
External characters: Similar to male
female gen. A. sparsana
Genitalia: Papillae analis and apophyses fairly large; sterigma broad, protruding in middle posteriorly with short, pointed anterior projections; ostium bursae rather rounded; antrum broad, transparent; ductus bursae long, heavily sclerotized in posterior half; corpus bursae elongate, large; dentate signum and sculptures (minute spines) in corpus bursae present.
Variation:
In the obscurely marked form a wide range of minor variation is found in the ferruginous striae which, when strong, may produce a slightly marbled effect. A very rare form occurs which lacks the ferruginous striae and has the forewing ground colour whitish grey, coarsely irrorate and striate along the veins with fuscous. Two major colour forms occur not infrequently; in one the forewing ground colour is light grey, the large triangular costal blotch and the basal fascia are reddish brown, well developed and conspicuous, the sub-basal fascia only weakly developed on the costa; in the other the forewing ground colour is whitish grey, the costal blotch greyish fuscous, well defined and conspicuous, and the basal and subbasal fasciae are well-developed on the costa (after Bradley et al., 1973).
Biology:
Adults appear in the late summer and autumn, hibernating in the winter and reappearing in the following spring. Larvae occur from June to late July or early August. Young larvae spin flimsy webs on the underside of expanded leaves. Older individuals occur between two overlapping leaves that they spin together with silk, sheltering in a folded portion of the upper leaf. Fully fed individuals pupate in July or August, either within the larval habitation or amongst debris on the ground (Alford, 1995).
Host plants:
Acer pseudoplatanus, Betula, Carpinus, Fagus sylvatica, Populus, Quercus, Rubus, Sorbus aucuparia.
Damage:
This species is a minor pest of beech and sycamore, oak, poplar, birch and rowan, and is often found on such hosts in parks and gardens. Larval feeding is restricted to the leaves and, although sometimes noticeable, is of no economic importance.
Distribution:
Europe from Orkney Is. to Caucasus; excl. southern regions (Greece, Southern Italy).
Pheromone:
Pheromone unknown.
Attractantia:
E 11-14Al : 9
Z 11-14Al : 1 (Booij and Voerman, 1985)