Agriculture Reference
In-Depth Information
blackish mark on the anterior margin; mainly
dusky yellow below.
Egg
1.3 mm long, yellow,
spindle-shaped and ribbed longitudinally.
Larva
up to 30 mm long;
body
velvet-green,
finely speckled with black, with a yellow line
along the back (absent in early instars) and
yellow markings along each side
(Plate
14c). Pupa
20 mm long, pale brown to grey or
pale greenish, with black markings.
Family LASIOCAMPIDAE
Malacosoma neustria
(L.)
Lackey moth
Fig.
303
Lackey moth,
Malacosoma neustria
(x3).
Minor infestations of this polyphagous species
sometimes occur on fruit trees. The gre-
garious larvae can cause extensive defoliation,
and this can have a detrimental effect on crop
yields.
Family GEOMETRIDAE
(geometer moths)
Abraxas grossulariata
(L.)
Magpie moth
BIOLOGY
Adults occur from late July to September. Eggs
are deposited in a batch around a twig and then
coated by the female with a varnish-like secre-
tion. The eggs hatch in the following spring and
the larvae then feed within a silken web which is
gradually extended as the larvae develop. When
leaves in the vicinity of the web are devoured the
larvae move to another branch and again form
a communal web. Pupation occurs in tough
double-walled cocoons on the host tree or
amongst debris on the ground. Adults emerge
about 3 weeks later.
This species is rarely of commercial significance
but it can cause defoliation of gooseberry bushes
in allotments and gardens; currant bushes,
plum trees and certain ornamental shrubs are
also attacked.
BIOLOGY
Adults occur in July and August. Eggs are
laid on the leaves of host plants and they hatch
about 2 weeks later. Young larvae feed briefly
and then overwinter. They become active again at
bud burst (much earlier than larvae of the com-
mon gooseberry sawffy,
Nematus ribesii,
p. 251).
When disturbed, larvae often drop from the foli-
age but will dangle on a thread of silk, adopting a
U-shaped posture. Larvae are fully grown in May
or June. They then pupate on the host plant, or on
nearby walls and fences, larvae at first spinning a
flimsy cocoon. Although this species is usually
single-brooded, under favourable conditions
there may be a partial second generation.
DESCRIPTION
Adult
30-40 mm wingspan;
forewings
pale
ochreous-brown to dark brown, often with a
broad, pale-bordered, median cross-band
(Fig. 303);
hindwings
pale ochreous brown to
dark brown;
antennae
bipectinate, more strongly
in male.
Larva
up to 50 mm long;
body
blue
with a white line along the back, and black-edged
red longitudinal lines along the back and sides;
body hairs
gingery;
head
blue, with two black
spots.
DESCRIPTION
Adult
35-40 mm wingspan, black and ochreous-
yellow;
forewings
mainly white with large black-
