Cydia fagiglandana

Author: (Zeller, 1841)

Beech moth

Species Overview:

Adult: 13-19 mm wingspan; forewing ground colour white or greyish white; basal blotch sharply angulated, with well-defined outer edge; fasciate markings obscure. Resembles Cydia splendana but differs by the more uniformly grey general appearance of the forewing, the ocellus being comparatively obscure and lacking the dark purplish colouration. The whitish grey patch of specialized scales on the hindwing in the male is characteristic.
Egg: deposited on the basis of the stigma of the blossom (beech) or on the fruits (chestnut).
Larva: up to 14 mm long; head light brown; prothoracic plates pale ochreous or reddish yellow; abdomen yellowish white, suffused with red dorsally, the suffusion forming indistinct longitudinal stripes, becoming orange when the larva is fully grown; pinacula orange.
Pupa: in a tough silken cocoon spun up amongst surface litter or sometimes in rotten wood or under bark or moss.

Taxonomic Description:

Male:

Cydia fagiglandana adult
Cydia fagiglandana adults
External characters: 13-19 mm wingspan. Forewing ground colour white or greyish white, suffused with grey and coarsely strigulated with dark brown, with a plumbeous admixture, the whole wing including fasciate markings profusely irrorate (tips of scales) with pale yellow-ochreous, producing a farinose effect, costa marked with black-brown strigulae, most conspicuous beyond middle, with two or three obscure plumbeous striae arising from interspaces, a variable and usually obscure, strigulated medio-dorsal blotch; fasciate markings obscure, greyish brown, obscurely strigulated with black-brown; basal and sub-basal fasciae forming a basal patch, its outer edge well defined, acutely angulated medially and often produced; median fascia narrow and outward-oblique on costa, obsolescent or interrupted above middle, broadening dorsally and confluent with subtriangular pre-tornal marking; ocellus large, variably developed, edged with metallic plumbeous striae and containing three or four variable, often diffuse, black dashes; sometimes an admixture of black above ocellus extending into apical area; cilia concolorous with wing basally, otherwise grey irrorate with white, with a dark brown sub-basal line often weakened or interrupted subapically. Hindwing fuscous, with an elongate patch of specialized whitish grey scales along inner margin on the upperside; cilia whitish grey, with a fuscous sub-basal line (Bradley et al., 1979).

male genitalia C. fagiglandana
Genitalia: Uncus and socii absent. Ventral margin of valva with slight notch; costal margin of valva strongly curved; cucullus large. Sacculus with setose tubercle under basal opening. Ridge cutting through neck of valve with sclerotized lamelliform protuberance, ridge does not reach basal opening. Aedeagus G-shaped.

Female

External characters: Forewing colouration and markings as in male; hindwing light fuscous.

female gen. C. fagiglandana
detail f. gen. C. fagiglandana
Genitalia: Sterigma with indistinct contours, uniform in structure, posterior margin convex. 7th sternite not sharply demarcated on sides. Papilla analis broad. Length of lobe about twice maximum width. Ductus seminalis originates close to corpus bursae, the latter with two signa.

Variation:

Minor variation is found in the general colouration and markings of the forewing, particularly in the depth and intensity of the yellow-ochreous irroration. The strength of the fasciate markings can also vary, as well as the clarity of the mediodorsal blotch. The black dashes in the ocellus are sometimes reduced to a few scales or they may be completely absent and the ocellus is unmarked (Bradley et al., 1979).

Biology:

Cydia fagiglandana is an univoltine species. The flight period of the adults is from May to July. The moths fly especially in the tops of their host trees. The eggs are deposited on the basis of the stigma of the blossom. On Fagus, the neonate larva eats itself through the still incomplete pericarp. The bore hole closes again and is no longer recognizable. Usually only one larva is found per beechnut, which is emptied by late August/early September (in Southern Sweden). Feeding continues until October in adjacent beechnuts. Mostly the larvae leave the beechnuts through an apical bore hole, before the nuts fall off the tree. The full-grown larvae are up to 14 mm long. The emptied beechnut is filled with faeces and maximally two exuviae. The larvae spin a cocoon in which they hibernate, either on the soil or inside the beechnuts. They leave these in spring. Pupation follows in April, and lasts some 15 days (variable).
On chestnut, Cydia fagiglandana is active between the end of flowering and the fall of the fruits. The eggs are deposited one by one on the fruits. Shortly after hatching the larvae bore into the fruit and seeds. Castanea and Quercus spp. have fruits large enough for a larva to complete its development on the same fruit. In fruits with small seeds (and some infertile) like those of Fagus sylvatica, they often need to change of fruit and seed (Bogensch├╝tz, 1991; Postner, 1978; Bovey, 1966; Bradley et al., 1979).

Host plants:

Fagus sylvatica (preferred), Castanea sativa, Quercus robur, Quercus ilex, Quercus suber, Quercus coccifera, Corylus.

Damage:

Larvae feed on the nuts. Strong infestations by Cydia fagiglandana can be discerned by the presence of empty (beech) nuts with emergence holes on the soil. The beechnut mast is occasionally very badly affected. Locally, up to 80% of the beechnuts in North-Western Europe are destroyed.
On chestnut the damage is similar to that caused by Cydia splendana.

Distribution:

Europe (closely related with the distribution of its preferred host - Fagus sylvatica) to Northern Iran and Central Asia; Madeira.

Pheromone:

E 8E 10-12Ac : 0.01 *
E 8E 10-12OH : 0.01
12Ac : 0.01 (Witzgall et al., 1996b)

Component marked with * is involved in attraction.

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