Agriculture Reference
In-Depth Information
Fig. 288
Forewings of
Cnephasia:
(a) flax tortrix
moth,
C. asseclana:
(b) light grey tortrix moth,
C. incertana
(x6).
Fig. 287
Female straw-coloured tortrix moth,
Clepsis
spectrana
(x6).
strawberry and sunflower. When disturbed,
unlike most other members of the family
Tortricidae, larvae of the genus
Cnephasia
usu-
ally do not wriggle backwards, but roll into a
tight 'C and drop to the ground.
fully grown, each pupates in its habitation
or amongst dead leaves. Adults emerge 2-3
weeks later. Second-generation larvae usually
overwinter whilst still very small and complete
their development in the spring. In glasshouses,
development may be continuous.
BIOLOGY
Adults are active from June to August. Eggs are
laid on fence posts, tree trunks or other struc-
tures 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
15-24 mm wingspan;
forewings
pale ochre-
ous-yellow to yellowish, with dark brown to
blackish markings;
hindwings
pale grey
(Fig.
287). Egg
orange, flat and oval.
Larva
up to
25 mm long;
body
greyish-green to brownish, but
paler dorsally;
pinacula
whitish;
head and
prothoracic plate
black or blackish-brown;
anal
plate
whitish-brown, with darker markings;
anal
comb
with six to eight teeth.
Pupa
10-14 mm
long, dull black;
cremaster
elongate, with stout
hooked spines (Fig. 283c).
Cnephasia asseclana
(Denis & Schiffermiiller)
Flax tortrix moth
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
This species is a potentially important pest of
various crops, the larvae (sometimes known as
'poppy leaf rollers') often feeding in large num-
bers on the leaves of lettuce, linseed, pea, poppy
and
Vicia
bean. Infestations also occur on vari-
ous other crops, including currant, raspberry,
