Cnephasia asseclana Denis Schiffermiiller Flax tortrix moth

This species is a potentially important pest of various crops, the larvae (sometimes known as 'poppy leaf rollers') often feeding in large numbers on the leaves of lettuce, linseed, pea, poppy and Vicia bean. Infestations also occur on various other crops, including currant, raspberry, strawberry and sunflower. When disturbed, unlike most other members of the family Tortricidae, larvae of the genus Cnephasia usually do not wriggle backwards, but roll into a tight 'C and drop to the ground.

BIOLOGY

Adults are active from June to August. Eggs are laid on fence posts, tree trunks or other structures and hatch about 3 weeks later. Apart from devouring their egg shells, the larvae do not feed until the following year. Instead, they form silken hibernacula in which to overwinter. In spring, the larvae invade various plants, at first mining the leaves and forming blotches. In their later instars, the larvae usually inhabit spun leaves (Plate 12c); they also attack open flowers. It is not uncommon, however, to find relatively large larvae still mining within leaves. When fully grown, the larvae pupate in spun leaves or amongst debris on the ground. Adults emerge shortly afterwards.

DESCRIPTION

Adult 15-18mm wingspan; forewings whitish-grey, more or less suffused with darker, often black-edged, markings (Fig. 288a); hindwings greyish-brown. Larva up to 14 mm long; body grey to greyish-green; pinacula black; head pale brown, marked with black; prothoracic plate and anal plate brown marked with black; anal comb

Fig. 289 Larva of flax tortrix moth, Cnephasia asseclana (x6): (a) anal comb (further enlarged).

present and with about six teeth (Fig. 289) (cf. Cnephasia incertana, p. 217). Pupa 7-8mm long; light brown; cremaster armed with spines which terminate in strong, noticeably thickened, hooks (cf. C. incertana, p. 217).

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