Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 326

871

870

870 Larva of heart & dart moth ( Agrotis exclamationis ). 871 Heart & dart moth ( Agrotis exclamationis ).

Agrotis exclamationis (Linnaeus) ( 870-871 )
Heart & dart moth
Generally abundant and sometimes a minor pest of
young trees and shrubs in nurseries. The larvae occur
from July onwards, at first feeding briefly on the foliage
of host plants but later, in common with related species
such as Agrotis segetum , attacking the roots and
adopting a typical 'cutworm' habit. Larvae (up to
38 mm long) are dull brownish to greenish brown, with
dark-edged longitudinal markings along the back and
relatively large, black spiracles. They complete their
development in the autumn but usually do not pupate
until the following spring. Adults occur in June and
July. Under favourable conditions, however, some
larvae pupate, to produce a partial second generation of
moths in the autumn. Adults (38-40 mm wingspan) are
whitish brown to dark brown, each fore wing including
a reniform stigma and a dart-like mark; the hind wings
are light greyish brown in females but whitish in males.

LIFE HISTORY
Adults occur from late May or June or early July,
depositing eggs on various weeds and cultivated plants.
The eggs hatch in about 1-3 weeks, depending on
temperature. Young larvae then browse on the foliage of
host plants, this feeding habit persisting for only the first
two instars. Older individuals inhabit the soil and
become typical sluggish 'cutworms', attacking the
roots, crowns and underground portions of plant stems.
Cutworms are active at night, resting during the day in
the soil close to their hosts. Most larvae are fully fed in
the autumn but they do not normally pupate until the
following spring; under favourable conditions, however,
some individuals develop more rapidly and give rise to
a small second generation of adults in the autumn.

DAMAGE
Larvae graze or burrow into corms, crowns, roots and
tubers, causing plants to wilt; also, stems of plants may
be girdled or completely severed, typically at about soil
level. Infestations are most severe on light soils and in
hot, dry conditions (cf. slug damage, p. 441), and tend
to be most significant on younger, unirrigated, slower-
growing hosts. Attacks in nurseries sometimes upset the
establishment and growth of seedling trees.

Allophyes oxyacanthae (Linnaeus) ( 872-873 )
syn. Meganephria oxyacanthae (Linnaeus)
Green-brindled crescent moth
Larvae of this widely distributed and often common
species feed on rosaceous trees and shrubs, including
blackthorn ( Prunus spinosa ), Cotoneaster , crab-apple
( Malus ) and hawthorn ( Crataegus ). Eggs laid in the
previous autumn hatch in the early spring. Larvae attack
the leaf buds and, later, the expanded foliage.
Individuals are rather plump ( c . 45 mm long when fully
grown), greyish brown to reddish brown, with small,
black-edged, pinkish-orange markings; the eighth
abdominal segment is slightly humped and bears two
pairs of pale projections. Feeding is completed by late
May or early June. Larvae then enter the soil and