Enarmonia formosana

Author: (Scopoli, 1763)

Cherry bark tortrix moth

Species Overview:

Adult: 15-19 mm wingspan; forewing ground colour white, overlaid with yellow-ochreous mixed with dark brown, giving it a brownish appearance. The distinctive colouration and markings of the forewing, especially the well-developed ocellus and the sharply defined costal strigulae in the apical half which are bordered dorsad by ferruginous-orange, are characteristic.
Egg: 0.7 x 0.6mm, lenticular; cream-white, becoming clear red after 2-3 days, the red colouration later being reduced to a semicircle. Deposited singly or in groups of two or three on smooth parts of the bark of the host tree.
Larva: 8-11 mm long; head brown, epistomal region blackish, mandibles large; prothoracic plate translucent anteriorly, becoming greyish brown medially and brown posteriorly, sometimes blackish markings or a patch on postero-lateral margin, medial sulcus greyish; abdomen shining translucent grey, pinacula a darker shining grey; anal plate shining grey speckled with dark grey; thoracic legs light brown [Enarmonia formosana larva ].
Pupa: 7-9 mm long; yellowish brown; spun up in the larval habitation.

Taxonomic Description:

Male:

Enarmonia formosana adult 1
Enarmonia formosana adult 2
Enarmonia formosana adult 3
External characters: 15-19 mm wingspan; forewing ground colour white, overlaid with yellow-ochreous mixed with dark brown except interspaces between distinct, black costal strigulae, these most conspicuous in apical half, thickly strigulated medially with metallic plumbeous, subcostal area overlaid with ferruginous-orange and containing a long submetallic plumbeous stria arising from the postmedian interspace and extending to terminal margin; markings dark brown mixed with yellow-ochreous; basal and sub-basal fasciae forming a poorly defined basal patch, its outer edge abruptly produced below middle, the projection sometimes extending to median fascia; median fascia irregular, narrow and usually well defined on costa, dilated before middle, confluent dorsally with pretornal marking; an irregular, quadrate blotch of ground colour on dorsum heavily strigulated with plumbeous; ocellus well developed, containing three or four thick black dashes narrowly separated by ferruginous-orange, edged laterally by thick lustrous plumbeous striae; subterminal fascia arising below middle of termen, curving above ocellus and confluent below costa with median fascia; cilia dark grey, a pair of yellow ochreous dashes subapically, a less conspicuous dash above tornus and another at tornus. Hindwing dark fuscous; cilia cream-white, sometimes suffused with fuscous, with a fuscous sub-basal line (Bradley et al., 1979).

male genitalia E. formosana
Genitalia: Tegumen long; uncus simple, rather weakly sclerotized, haired dorso-laterally; socii broad, lateral, hairy; tuba analis membranous. Valva small, with elongated basal opening, neck indistinct; cucullus small, bristled, expanding terminally, provided with short modified setae before apex. Aedeagus simple; cornuti missing.

Female:

External characters: Similar to male.

female genitalia E. formosana
Genitalia: Sterigma completely reduced; distal part of ductus bursae forming a short, sclerotic tube; ductus seminalis extending from mid-part of ductus bursae. Only one signum present in corpus bursae: a triangular, concave plate.

Biology

Enarmonia formosana is bivoltine under Western European conditions, moths flying from May to September. Eggs are laid separately or in small groups on the bark, close to rough parts or wounds. They hatch in two to three weeks and the larvae then start to bore into the bark and feed underneath the surface. Wound tissue, graft point and the base of the trunk are favourite sites for larval infestations. The tunneling of the larva causes large masses of gum to exude from the bark. Successive generations seem to use the same tunnels. The larvae work their way towards the bark before they develop into pupae, which are contained in cocoons, located in tunnels close to the surface. Alternate generations of larvae hibernate, ranging from second instar to full-grown larvae (Dickler, 1991; Van de Vrie, 1991; Alford, 1984; Bradley et al., 1979).

Host plants:

This species infests numerous species of fruit trees, including (Prunus, Malus, Pyrus), in order of preference, almond, apricot, peach, cherry, plum, apple and pear (Dickler, 1991).

Damage:

damage on bark of plum tree
piles of excrements (formosana)
Larvae excavate irregular, often deep galleries in the bark, members of successive generations feeding within and considerably enlarging the same burrows. Most feeding occurs in the bark tissue; the underlying cambium may also be damaged but tunnels do not extend into the wood. Attacks are normally established only on older and, often, previously injured trees. For example, they are often initiated in frost-damaged bark or adjacent to pruning wounds and other mechanically injured areas. Especially on cherry and plum, a considerable quantity of gum may exude from infested parts of host trees and this, along with accumulations of light brown frass and silken webbing forced out of cracks in the bark, may be one of the first indications of an attack. Cherry trees are usually infested near the base of the trunks but apple trees, especially large ones, are frequently damaged below the main branches, close to the trunk, and on the trunk near such areas. Infestations produce cracks, swellings and cankers; branches or whole trees may be killed (Alford, 1984).
Prunus triloba is also attacked. This rich flowering Prunus species is cultured as a small tree in the open. In autumn, the trees are grubbed and forced in greenhouses for early flowering. Larvae burrow tunnels under the bark, causing gum to exude from the stem, which often results in the death of the tree. Enarmonia formosana is its principal insect pest in the Netherlands (Van de Vrie, 1991).

Distribution:

Western Europe, from UK and Scandinavia to the Mediterranean Sea; Asia Minor, Kazakhstan; Russia to Siberia and Primo're; Northern Africa; North America.

Pheromone:

Z 9-12Ac 60
E 9-12Ac 40
Z 7-10Ac 1 (McNair, 1996)

Attractantia:

Z 9-12Ac 1
E 9-12Ac 1 (Minks et al., 1976)

or

Z 8-12Ac 100
E 8-12Ac <2 (Hrdy et al., 1979)

Parasitoids:

Campoplex punctulatus (Sz├ępligeti) (Ichneumonidae)
(Van de Vrie, 1991)

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