Agriculture Reference
In-Depth Information
DESCRIPTION
Adult 15-22 mm wingspan; forewings whitish-
ochreous to brownish-ochreous (in the female
with darker markings); hindwings light grey.
Larva up to 18 mm long; body greenish-grey to
yellowish-grey, with pale stripes along the back;
head light brown; prothoracic plate and anal plate
light brown (Plate 12d). Pupa 7-8 mm long,
light brown.
Cnephasia pumicana (Zeller)
larva = Cereal leaf roller
This species is associated mainly with cereals,
and is reported as a potentially important pest in
parts of continental Europe, especially northern
France. The larvae also feed on various other
plants, although on many such 'hosts' they can-
not complete their full development. Most sig-
nificant damage is caused to the ears of wheat
and barley. In some instances, grains are totally
destroyed or their development aborted. In
other cases, following damage to the stem above
the top-most node, the ear turns white; on bar-
ley, yield losses of over 20% are reported. This
pest does not occur in the British Isles.
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).
BIOLOGY
Adults are active in July. Eggs are then laid on
the bark of trees and on other similar surfaces.
First-instar larvae appear in August and then
almost immediately spin hibernacula within
which to overwinter. Larvae reappear in the
spring, usually from March onwards. They then
produce a line of silk and are carried by the wind
until they alight on a suitable host plant. On
cereals, the larvae at first mine within the leaves.
In the later stages of their development, the lar-
vae feed externally, attacking the stems and the
developing ears. Fully fed larvae pupate within
the shelter of the ear sheath and adults emerge
2-3 weeks later. There is just one generation
annually.
Cnephasia longana (Haworth)
larva = Omnivorous leaf tier
This locally common pest is polyphagous, but
associated mainly with wild Asteraceae, includ-
ing thistles. Crops attacked include apple, barley,
bean, beet, linseed, maize, strawberry and wheat.
BIOLOGY
Moths are active in July and their eggs are then
laid on tree trunks and other surfaces. The larvae
overwinter in silken hibernacula, having fed only
on their egg shells. In spring they invade various
host plants and usually inhabit folded leaves or a
shelter of webbed-down petals. They complete
their development in June and then pupate in a
silken cocoon on the host plant. Adults emerge
2-3 weeks later.
DESCRIPTION
Adult 16-20 mm wingspan; forewings mainly
yellowish-grey; hindwings pale yellowish-grey.
Egg 1 mm long, elliptical, pale yellowish-orange
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