Agriculture Reference
In-Depth Information
Fig. 317
Part of antenna of
Agrotis:
(a) turnip moth,
A. segetum;
(b) heart & dart moth,
A. exclamationis.
Fig. 316
Forewings of
Agrotis:
(a) turnip moth,
A.
segetum:
(b) heart & dart moth,
A. exclamationis
(x3).
their stems partially severed; recent transplants
and seedlings are worst affected.
Potato:
roots
and stems are severed and tubers hollowed out
(Plate 14e);
the most significant damage is
caused before July.
BIOLOGY
Adults fly from late May to June or early July.
Eggs are laid in batches on the leaves of various
host plants and hatch within approximately 3
weeks. Young larvae feed on the leaves but, on
attaining the third instar, they become subterra-
nean and act as typical 'cutworms'. They are ac-
tive at night but, during the daytime, may be
found resting in the soil close to plant roots.
Most larvae are fully fed by the autumn. They
then overwinter and pupate in the spring, each in
an earthen cell. Under favourable conditions,
however, some larvae will pupate before
overwintering to produce a partial second gen-
eration of adults in the autumn. Survival of this
species is greatly hampered by rainfall during the
critical early stages of larval development.
(b)
Fig. 318
Frontal view of head of cutworms:
(a) turnip moth,
Agrotis segetum;
(b) heart & dart
moth,
A. exclamationis.
pearly-white;
antennae of male
bipectinate
(Fig.
317a). Egg
0.6mm diameter, pale grey to
creamish, hemispherical and distinctly ribbed.
Larva
up to 35 mm long;
body
plump; glossy
greyish-brown, with a yellowish or pinkish tinge
and indistinct darkish lines along the back;
pinacula
black;
head
yellowish-brown;
adfrontal
plates
blunt at apex
(Fig. 318a)
(cf.
Agrotis
exclamationis,
p. 236);
mandibles
elongate (cf.
DESCRIPTION
Adult
38-44 mm wingspan;
forewings
whitish-
brown with brownish-black or blackish-edged
markings, including a basal dash and two
subcentral stigmata
(Fig. 316a);
hindwings
