Author: (Thunberg, 1797)
Polyphagous leaf roller
Species Overview:
Adult: 12-16 mm wingspan; forewing ground colour silver-white, strigulated with grey; markings dark reddish brown, sprinkled with black; margins of basal and median fasciae irregular. Hindwing grey.
Egg: yellow, turning brown during development; deposited in batches of 40-50 eggs, usually on the upper surface of the leaves of the food plant.
Larva: head light green or yellowish green, epicranium darker posteriorly; prothoracic plate yellowish green with blackish postero-lateral stripe, posterior margin narrowly edged with black; abdomen clear green, sometimes tinged with brown; pinacula indistinct, paler than integument; anal comb present, bearing 6-8 prongs.
Pupa: pale brown; in a silken cocoon in spun leaves in, or overwintering in a cocoon in debris on the ground.
Taxonomic Description:
Male:
Argyrotaenia ljungiana male 1
Argyrotaenia ljungiana male 2
External characters: 12-16 mm wingspan. Antenna of male shortly ciliate. Forewing long and slender; ground colour silver-white, strigulated with grey; markings dark reddish brown, sprinkled with black; margins of basal and median fasciae irregular. Costal fold absent. Hindwing grey; cilia whitish (Bradley et al., 1973).
male genitalia A. ljungiana
Genitalia: Uncus narrow and long; gnathos simple; socii absent; vinculum with distal fold sclerotized only subventrally. Valva elongate-ovate, provided with weak sclerite and curved, longitudinal folds beneath middle of disc; sacculus slender, without free end; transtilla narrow, glabrous. Aedeagus with group of short cornuti (about 10) in vesica. Androconial apparatus in male in form of two clusters of piliform scales, covered in hidden lateral pockets before valva.
Female:
Argyrotaenia ljungiana female 1
Argyrotaenia ljungiana female 2
External characters: Apex of the forewing usually slightly more pronounced than in the male; colour and markings similar to male.
female gen. A. ljungiana
Genitalia: Sterigma concave in middle dorsally, with distinctly sclerotized anterior edge and lateral arms which taper terminally; antrum not broader than ductus bursae; ductus bursae short, with plate-shaped, folded sclerite in basal portion; signum large.
Variation:
The usually conspicuous silver-white ground colour of the forewing may be obscured to varying degrees by greyish suffusion; the reddish-brown markings are sometimes more liberally sprinkled with black, the general colouration then appearing comparatively sombre. The markings are very irregular and variable, and frequently the median fascia is broader, reducing the whitish ground colour (Bradley et al., 1973).
Biology:
The female deposits her eggs in batches of 40-50 eggs, usually on the upper surface of the leaves of the food plant. They hatch in 10-21 days. The newly hatched larvae skeletonize the underside of the leaf along the midrib, and later disperse and feed in spun leaves. Pupation occurs in a silken cocoon in spun leaves. The pupa develops in 7-10 days.
The number of generations yearly varies. In Poland, the Netherlands, the south of the British Isles and the northern parts of Italy, the species is bivoltine, the first generation occurring in April and May, the second from the end of June to July or August. In the north of the British Isles, it is univoltine, occurring from the end of April to June. In the Mediterranean area, the species has three generations per year. Argyrotaenia ljungiana overwinters in the pupal stage, in a cocoon in debris on the ground.
Host plants:
Abies, Acer, Artemisia vulgaris, Aster, Betula, Bohemia nivea, Calluna, Centaurea, Crataegus, Dryas octopetala, Erica, Evonymus, Genista, Gentiana pneumonanthe, Helichrysum, Hibiscus, Humulus, Larix, Malus, Myrica, Phaseolus, Pimpinella saxifraga, Picea, Pinus, Prunus, Populus, Potentilla, Pyrus, Quercus, Ranunculus, Rhamnus, Senecio, Solidago, Vaccinium , Vitis.
Damage:
Argyrotaenia webbing of Picea needles
Larvae web leaves or needles together and also attack the fruits. This species has become a minor pest of Vitis (grapes) and Malus (apple).
Distribution:
Palaearctic Region excl. Japan.
Pheromone:
Z 11-14Ac : 76 *
E 11-14Ac : 19 *
Z 11-14OH : 2
14Ac : 5
21Hv
22Hv
23Hv (Frérot et al., 1984)
Components marked with * are involved in attraction.
Parasitoids:
Colpoclypeus florus (Walker) (Eulophidae)
Meteorus ictericus (Nees) (Braconidae)