Agriculture Reference
In-Depth Information
the male, occasionally with a few black dots);
hindwings
white.
Larva
up to 40mm long;
body
black with white subdorsal patches, a pair of
sometimes indistinct broken red lines along the
back, and tufts of gingery hair arising from
prominent black warts; a prominent orange-red
spot (gland) on the sixth and another on the
seventh abdominal segment;
head
black and
shiny
(Plate 14d).
Orgyia antiqua
(L.)
Vapourer moth
Although mainly of significance as a defoliator of
specimen trees in towns and cities, larvae of this
pest also attack fruit trees. Damage on fruit
crops, however, is rarely of significance.
Fig.
315
Male vapourer moth,
Orgyia antiqua
(x3).
long;
body
dark grey with tufts of greyish-white
hairs arising from reddish warts; a pair of long,
forward-directed tufts (pencils) of black hairs
arising from the first thoracic segment; a long,
posterior-directed tuft of hair arising from the
centre of the seventh abdominal segment; brush-
like tufts of yellow hairs on abdominal segments
1-4 (see Fig. 139);
head
black and shiny.
BIOLOGY
Adults occur from July to September. The flight-
less females are sedentary and, following their
emergence, stay on the remains of the pupal co-
coon. Males, however, are very active and, in
sunny weather, fly rapidly in search of newly
emerged females. Eggs are laid in a large batch
of several hundred on the outer surface of the
pupal cocoon; the female then dies. The eggs
overwinter and hatch over an extended period
from May onwards. Larvae feed avidly on foliage
and are very active, often migrating from one
host plant to another. When fully grown, the
larvae spin large pupal cocoons on tree trunks or
branches; pupal cocoons are also often formed
on walls and fences some distance from the final
foodplant. Although usually univoltine, in fa
vourable situations there may be two or more
generations annually.
Family NOCTUIDAE
Agrotis segetum
(Denis & Schiffermuller)
Turnip moth
The turnip moth is a major pest of vegetable
crops such as carrot, leek, lettuce, onion, parsnip,
potato, red beet and turnip; it is also a minor
problem on cereals, strawberry and various or-
namental plants. The larvae damage plants at or
about soil level, often causing them to wilt and
die. Attacks are particularly severe in light soil
during hot, dry summers and tend to be most
significant on younger, unirrigated, slower-
growing hosts, including seedlings and recent
transplants.
Carrot, red beet and other root veg-
etables:
larvae hollow out large cavities in the tap
root, destroying roots or reducing their market-
ability.
Leek:
attacked plants develop distorted
top-growth, and the stems become characteristi-
cally twisted.
Lettuce:
plants are very susceptible
to damage, often being cut off at ground level or
DESCRIPTION
Adult female
10-15 mm long, plump-bodied,
dark yellowish-grey and virtually wingless.
Adult male
25-33 mm wingspan;
forewings
ochreous-brown to chestnut-brown, with dark
wavy cross-lines and a white spot close towards
the hind angle;
hindwings
ochreous-brown to
chestnut-brown
(Fig. 315). Egg
0.9mm in di-
ameter, pale brownish-grey.
Larva
up to 35 mm
