Biology Reference
In-Depth Information
1005
1006
1005
Larva of
Nematus umbratus
.
1006
Adult of
Nematus umbratus
.
1007
1008
1007
Larva of
Nematus viridescens
.
1008
Adult of
Nematus viridescens
.
Nematus umbratus
Thomson (
1005-1006
)
syn.
N. collinus
Cameron;
N. similis
(Forsius)
A gregarious species, associated with birch (
Betula
);
sometimes damaging to young nursery or amenity trees
but usually uncommon. The larvae (up to 25 mm long)
are blackish green to whitish green, shiny and
translucent. They feed gregariously from May onwards,
causing considerable damage to the foliage. There are
two generations annually, the mainly yellowish-orange
adults (5.5-7.5 mm long) occurring from May to June
and from late July to early September.
Periclista lineolata
(Klug) (
1009-1011
)
A locally common but minor pest of oak (
Quercus
),
especially English oak (
Q. robur
). Widely distributed in
central and northern Europe.
DESCRIPTION
Adult:
5-6 mm long; mainly shiny black with a short
greyish or whitish pubescence; tegulae, edge of
pronotum, knees and tibiae whitish; wings hyaline and
iridescent, with black veins and each fore wing with a
black pterostigma.
Larva:
up to 17 mm long; head
black; body green with numerous black, mainly
Y-shaped spines along the back and sides, and a series
of smaller spines (some Y-shaped and some simple)
above the legs.
Nematus viridescens
Cameron (
1007-1008
)
A generally common species, associated with birch
(
Betula
); sometimes present on nursery trees and young
ornamentals but not an important pest. Adults occur
from April onwards. The mainly green larvae feed on
the leaves during the summer and autumn. There are
two or more generations annually. Adults (6-8 mm
long) are mainly green.
LIFE HISTORY
Adults occur in April and May, eggs then being laid
close to the veins of unfurling leaves. The larvae feed on
the underside of oak leaves from mid-May to mid-June,
making large holes in the leaves. When fully grown they
moult to a mobile prepupal stage (which is devoid of
Search WWH ::
Custom Search