Author: (Denis and Schiffermüller, 1775)
Flax tortrix moth
Species Overview:
Adult: 15-18 mm wingspan; forewings whitish-grey suffused with black, with dark yellowish-brown, blackish-edged markings; hindwings greyish-brown.
Egg: 0.5-0.6 mm x 0.3 mm, flat and oval; yellowish-white to greenish-yellow [Cnephasia asseclana egg]; deposited on the food plant in small batches, covered with scales.
Larva: 12-14 mm long; grey or bluish-white to dark cream or yellowish green, with black pinacula; head pale or yellowish brown, marked with black; prothoracic plate light brownish to dark brown, marked with black; anal comb with about six long teeth; thoracic legs light to dark brown; prolegs marked with grey or black [Cnephasia asseclana larva].
Pupa: 7-8 mm long; light brown; setae on cremaster noticeably thickened away from their point of origin, bent into stout hooks terminally; a distinct transverse ridge ventrad of the short cremaster spines; in the folded edge of a leaf or in debris on the ground [cremaster pupa C. asseclana ].
Taxonomic Description:
Male:
Cnephasia asseclana adult
C. asseclana adults
Cnephasia asseclana male
External characters: 15-18 mm wingspan. Antenna very shortly ciliate. Costal margin of forewing arcuate, apex delicately rounded; termen oblique. Ground colour whitish grey coarsely irrorate and suffused with fuscous; markings diffuse, dark brown finely irrorate with ochreous, sprinkled and weakly edged with blackish brown; sub-basal fascia very weak or obsolete near dorsum, outer margin diffuse, produced medially and often connected to the comparatively narrow median fascia; pre-apical spot diffuse, often connected to median fascia, usually extending to termen. Hindwing greyish brown, darker distally (Bradley et al., 1973).
male genitalia C. asseclana
Genitalia: Valva of variable shape, broad; sacculus variable, fairly short, the separate tip of sacculus sometimes extending beyond the apex of valva; aedeagus short, strongly tapered and acuminate terminally; uncus long, socii fairly small.
Female:
Cnephasia asseclana female
External characters: Colour and markings similar to male.
female genitalia C. asseclana
Genitalia: Antrum broad, weakly sclerotized; lamella antevaginalis broad; ductus bursae short; ductus seminalis situated medially. Signum large, drop-shaped.
Variation:
This species shows considerable minor variation in the ground colour and markings of the forewing; occasionally specimens occur with heavier and relatively distinct markings on the normal whitish grey ground colour, but more often the latter is darkened by a heavy greyish suffusion and the markings are less distinct. Melanistic forms occur in which the markings are very indistinct and mostly represented by black specks; in extreme forms the wing may be almost unicolorous blackish brown.
Biology:
Moths occur from June to August. Eggs are deposited, either singly or in small batches, on herbaceous plants, tree trunks, posts or other supports. They hatch in about three weeks and the larvae then spin small hibernacular cocoons in a suitable shelter nearby, having fed only on their egg shells. Activity is resumed early in the following spring, the first-instar larvae mining leaves to feed in irregular, usually blotch-like mines. Later each larva feeds amongst spun leaves or on a flower, spinning the petals down with silk to form a 'capped' blossom. If disturbed, the larvae roll into a tight 'C' and drop to the ground. Pupation takes place in June in the folded edge of a leaf or amongst debris on the ground (Alford, 1984; Alford, 1995).
Host plants:
Polyphagous on herbaceous plants, including garden and glasshouse-grown ornamentals, such as Chrysanthemum, golden rod (Solidago), Helenium, Pelargonium, Phlox, primrose (Primula), Rudbeckia and sweet pea (Lathyrus doratus). Also recorded from cultivated strawberry, raspberry, garden beans, lucerne, linseed and spruce.
Hering, 1957, and Kurir, 1975, provide lists of plants on which larvae have been found:
Acer, Achillea, Aegopodium, Agrimonia, Agrostemma, Ajuga, Alchemilla, Anchusa, Anemone, Antennaria, Anthyllis, Aquilegia, Arabis, Arctium, Artemisia, Aster, Atriplex, Bellis, Beta, Borago, Brassica, Calendula, Caltha, Campanula, Carum, Centaurea, Cerastium, Chaerophyllum, Chenopodium, Chrysanthemum, Cirsium, Claytonia, Conopodium, Coronilla, Cortusa, Crepis, Cynoglossum, Dactylis, Datura, Dianthus, Digitalis, Diplotaxis, Echium, Eranthis, Eupatorium, Euphorbia, Fagopyrum, Fagus, Fragaria, Fumaria, Galega, Genista, Gentiana, Geranium, Geum, Glechoma, Glyceria, Heracleum, Hieracium, Hypericum, Hypochoeris, Iberis, Impatiens, Isatis, Kickxia, Lapsana, Lathyrus, Leontodon, Linaria, Lotus, Lunaria, Lupinus, Malva, Malus, Matricaria, Medicago, Melampyrum, Melilotus, Mentha, Menyanthes, Milium, Mimulus, Myosotis, Onobrychis, Ononis, Origanum, Oxyria, Papaver, Peucedanum, Phaca, Phacelia, Phaseolus, Pisum, Plantago, Poa, Polemonium, Polygonum, Potentilla, Prenanthes, Primula, Prunella, Pulicaria, Ranunculus, Raphanus, Rheum, Rhunanthus, Rosa, Rubus, Rumex, Salix, Salvia, Saxifraga, Scabiosa, Scrophularia, Sedum, Senecio, Sinapis, Sisymbrium, Solidago, Stachys, Stellaria, Taraxacum, Teucrium, Trifolium, Trigonella, Trollius, Tulipa, Tussilago, Vaccinium, Valeriana, Verbascum, Verbena, Veronica, Vicia, Viola, Vitis, Zinnia.
Damage:
This species is sometimes a pest of garden and glasshouse-grown ornamentals. Attacks are usually of only minor importance but infestations, especially on flowers, may affect the marketability of commercial pot plants. When feeding on the flowers of Chrysanthemum, the larva spins the leaves and a flower bud together, causing the bud to bend over at an angle of 90 degrees, and eats into it from beneath.
On strawberry, larvae are usually feeding on the flowers.
Distribution:
Europe to Siberia; Canary Islands; Newfoundland.
Pheromone:
Pheromone unknown.
Attractantia:
E 9-12Ac (Booij and Voerman, 1984a)
or
E 10-12Ac (Priesner, 1986)
Parasitoids:
Angitia fenestralis Holmgren (Ichneumonidae)
Angitia rufipes Gravenhorst (Ichneumonidae)
Cryptopimpla errabunda Gravenhorst (Ichneumonidae)
Itoplectis maculator Fabricius (Ichneumonidae)
Omorgus mutabilis Holmgren (Ichneumonidae)
Scambus brevicornis Gravenhorst (Ichneumonidae)
Bracon caudiger Nees von Esenbeck (Braconidae)
Meteorus chrysophthalmus Nees von Esenbeck (Braconidae)
Meteorus gyrator Thunberg (Braconidae)
Microbracon hebetor Goid (Braconidae)
Microgaster nitidulus Wesmael (Braconidae)
Microgaster tibialis Nees von Esenbeck (Braconidae)
Microgaster tiro Reinhard (Braconidae)