Main Insect Orders - Agricultural Entomology - page 225

13c); hindwings pale creamish-white with pale
greyish markings and a dark submarginal
line. Larva up to 18mm long; body greenish to
yellowish and somewhat translucent, with a
dark, dorsal stripe and a pale spiracular stripe,
small black spiracles and pale hairs (Plate 13d);
fully fed individuals are distinctly glossy;
head and prothoracic plate brownish-green to
yellowish-green.

Fig. 301 Forewing of sunflower moth, Homoeosoma
nebulella (x5).

Homoeosoma nebulella
(Denis & Schiffermiiller)
Sunflower moth

Margaritia sticticalis (L.)
larva = Beet webworm

Larvae of this species feed mainly on Artemisia
vulgaris but they will also attack sugar beet,
spinning the leaves of young plants together;
when numerous, the larvae cause extensive
defoliation but the major veins are left
intact. Although an important pest in continental
Europe and in North America, it is of little or
no importance in Britain, where it occurs mainly
in sandy districts such as the Brecklands of
East Anglia.

This moth is associated with various members of
the Asteraceae and, in the warmer parts of con-
tinental Europe, is a pest of sunflower. The lar-
vae feed on the inflorescences of host plants, at
first devouring pollen but later burrowing into
the flowers or maturing seeds. In severe cases
over a quarter of sunflower seed yields may be
lost. Although present and widely distributed in
England, this species is not of pest status in the
British Isles.

BIOLOGY
Adults occur in June and there may be a
partial second flight in August and September.
Although active mainly at night, the moths
sometimes also fly in hot, sunny weather.
Eggs are laid on the leaves of host plants, mainly
in early June. They hatch shortly afterwards.
Larvae then feed on the leaves, and often
web leaves together to form a tube which ex-
tends down to the soil surface. The larvae are
very active and, when disturbed, will move
rapidly backwards and often seek shelter in
cracks in the soil. The winter is passed in the
pupal stage.

BIOLOGY
Larvae of the first generation occur on wild
hosts, usually feeding in late May and early June.
Sunflower crops are attacked by larvae of the
second generation, rather than the first, as eggs
will not be deposited unless flowers are produc-
ing pollen. Attacks will continue into early win-
ter, so long as the crop has not been harvested
and suitable flowers are still available. The pest
usually completes two or three generations in a
season.

DESCRIPTION
Adult 22-27 mm wingspan; forewings ash-
grey with a brownish sheen, and each marked
with a few scattered dark spots (Fig. 301);
hindwings pearly and translucent. Egg 1mm
long, yellowish-white. Larva up to 14 mm long;
body pale greenish-yellow to dirty grey, marked
with reddish or purplish dorsal, subdorsal and
spiracular lines; head brown; prothoracic plate
green.

DESCRIPTION
Adult 20-25 mm wingspan; forewings brownish-
black with a creamish subcentral spot and pale
submarginal markings (Fig. 302); hindwings pale
brownish-black. Larva up to 25 mm long; body
slender, grey to yellowish; pinacula pale, black-
edged; head black; prothoracic plate black or
grey.