Author: (Clerck, 1759)
Species Overview:
Adult: wingspan 20-23 mm in males; forewing elongate, slate-grey with whitish admixture, median area of wing from base to end of cell and in distal area strongly overlaid with white, producing a silver-grey effect, with blackish fuscous markings. Hindwing greyish fuscous.
Females brachypterous; 10-11 mm wingspan. Forewing whitish grey, margins spotted with diffuse fuscous markings.
Egg: deposited singly or in small batches of three or four eggs on the stems and twigs of the food plant; hatching in late spring.
Larva: head yellowish green, spotted with black laterally; prothoracic plate yellowish green, flecked with black posteriorly; abdomen light green, a paler subdorsal line, integument shagreened.
Pupa: dark brown; spun up in debris on the ground.
Taxonomic Description:
Male:
Exapate congelatella male 1
Exapate congelatella male 2
External characters: 20-23 mm wingspan. Antenna ciliate, length of cilia less than width of flagellum. Forewing elongate; costal margin straight, termen oblique. Ground colour slate-grey with whitish admixture, median area of wing from base to end of cell and in distal area strongly overlaid with white, producing a silver-grey effect; markings blackish fuscous; basal fasciae obsolete; median fascia reduced to form a large orbicular spot below costa; a smaller spot at end of cell connected to dorsum by a fuscous suffusion; pre-apical spot represented by several chevron-like inwardly oblique striae. Hindwing greyish fuscous; cilia concolorous, with a distinct fuscous basal line (Bradley et al., 1973).
male genitalia E. congelatella
Genitalia: Uncus on a distinct neck, short, not spined, with broad basal lobes armed with minute spines; socius delicate; gnathos strong, with distal parts of arms covered with spines and with elongate terminal plate. Valva with inwardly curved process before midpoint of ventral margin. Transtilla with delicate, spined median part; juxta provided with long dorso-lateral processes. Aedeagus thin, small.
Female:
Exapate congelatella female 1
Exapate congelatella female 2
External characters: 10-11 mm wingspan, wings vestigial. Antenna sparsely hirsute, with bristle-like hairs two to three times width of flagellum basally, slightly shorter apically. Forewing whitish grey, margins spotted with diffuse fuscous markings; median fascia indicated on costa; hindwing reduced, pad-like; wings, body and appendages clad with moderately dense erect brownish hairs interspersed among the scales.
female gen. E. congelatella
Genitalia: Sterigma plate-shaped, in distal portion membranous; colliculum small, rather strongly sclerotized. Ductus seminalis posterior; signum absent.
Variation:
The forewing colouration and markings of the male are relatively constant except for slight variation in the intensity of the white scaling; specimens in which this is weak usually have a greyer appearance and the markings are less distinct. Variation in the female is most apparent in the irregular distribution of the fuscous spotting on the forewing (Bradley et al., 1973).
Biology:
There is a single generation yearly. Exapate congelatella is one of the latest species to emerge in the year. Moths fly from October to December, the males flying freely an hour before dusk and often found assembling to a freshly emerged female. The brachypterous female may be found after dusk at rest on the food plants, often on the tips of the shoots. Eggs are deposited singly or in small batches of three or four eggs on the stems and twigs of the food plant. They overwinter and hatch in late spring. Larva feed in spun shoots, from May to early July. Pupation occurs from June to October, spun up in debris on the ground (Bradley et al., 1973; Bovey, 1966).
Host plants:
Anthriscus, Berberis, Calluna, Chaerophyllum, Crataegus, Erica, Fragaria, Ligustrum, Myrica, Prunus , Pyrus, Rhamnus, Ribes, Rubus, Salix, Syringa, Ulmus,
Damage:
Larvae skeletonize rolled leaves; thereafter cut leaves and damage flowers and ovaries. It is only known as a fruit pest in northern Europe.
Distribution:
Northern and Central Europe to Kazakhstan; South-Western China.
Pheromone:
Pheromone unknown.
Attractantia:
Z 11-14Ac : 3
E 11-14Ac : 1
(Velcheva and Milkova, 1990)
Exapate duratella Heyden
The Alpine species Exapate duratella Heyden, (often associated with conifers) exhibits according to Kuznetsov, 1987, no reliable morphological differences from Exapate congelatella.