Biology Reference
In-Depth Information
Pristiphora wesmaeli
(Tischbein) (
1034
)
Larch sawfly
A widely distributed pest of larch (
Larix
), particularly
young trees; of greatest importance in forestry
plantations but sometimes also present on ornamentals.
The mainly yellow, black-marked adults (5.0-6.5 mm
long) occur from May to June or early July, eggs being
deposited in young needles at the tips of new shoots. The
larvae (up to 18 mm long) are green, with a yellowish-
green head. They feed during the summer, often
stripping the needles from the terminal shoots.
Rhadinoceraea micans
(Klug) (
1038
)
Iris sawfly
A locally distributed pest of mainly waterside irises,
occurring on wild yellow flag (
Iris pseudacorus
) and
also cultivated species such as
I. laevigata
and butterfly
iris (
I. spuria
). Most common in central Europe; in
Britain found mainly in the southern half of England.
DESCRIPTION
Adult:
7-8 mm long; body black and stout; wings
slightly smoky.
Larva:
up to 20 mm long; head black;
body bluish grey to dirty greenish yellow, with pale
verrucae on the back and sides.
Profenusa pygmaea
(Klug) (
1035
)
Oak leaf-mining sawfly
This widely distributed, locally common leaf miner is
associated with English oak (
Quercus robur
) and sessile
oak (
Q. petraea
), including young trees. The larvae
mine the upper side of the leaves in the summer and
early autumn, forming prominent, brown blotches.
These mines are disfiguring but they do not affect plant
growth. When fully fed the larvae vacate the mines to
overwinter in the soil. Adult females (3-4 mm long) are
black, with white tegulae, knees, tibiae and tarsi. They
occur from May to July. Males are unknown, and
reproduction is entirely parthenogenetic. The larvae (up
to 8 mm long) are white, with a light brown head, a
black prothoracic plate and black plates between the
thoracic legs; abdominal prolegs are absent.
LIFE HISTORY
Adults occur in May and June, depositing eggs on the
leaves of irises. The larvae feed from late May onwards,
most completing their development by the end of July.
They then enter the soil and spin silken cocoons in
which to pupate. There is just one generation annually.
DAMAGE
Young larvae bite out V-shaped wedges along the leaf
edges; older larvae graze away longitudinal sections of
the leaf margins, feeding from the tips downwards and
eventually reducing the foliage to ragged stumps.
Larvae also attack flower buds.
Scolioneura betuleti
(Klug) (
1039
)
syn.
S. betulae
(Zaddach)
A generally common pest of birch (
Betula
), and often
injurious to young amenity trees and nursery stock.
Widely distributed in central and northern Europe.
Protemphytus carpini
(Hartig) (
1036-1037
)
syn.
P. glottianus
Cameron;
Ametastegia carpini
(Hartig)
Geranium sawfly
This widely distributed species is associated with
Geranium
, including cultivated forms, on which the
larvae cause noticeable leaf damage. Larvae (up to
12 mm long) are mainly olive-green to greyish black,
but paler below. There are two generations annually.
Adults (6-8 mm long) are mainly black and shiny; they
occur from May to June and from July to August.
DESCRIPTION
Adult:
4-5 mm long; shiny black and slender bodied,
with mainly reddish-yellow legs.
Larva:
up to 10 mm
long; white with a brown head, a large prothoracic plate
and a large plate ventrally on the first thoracic segment;
distinct black markings usually present ventrally on the
remaining two thoracic and first (sometimes also
second) abdominal segments, plus a pair of marks
ventrally on the penultimate abdominal segment; black
markings also present along the sides; legs banded with
black.
Protemphytus pallipes
(Spinola)
syn.
P. grossulariae
(Klug);
Ametastegia pallipes
(Spinola)
Viola sawfly
An extremely widespread pest of
Viola
, including pansy
(
V. tricolor
) and sweet violet (
V. odorata
); often present
on cultivated plants. Adults (6-8 mm long) are mainly
black; the larvae (up to 10 mm long) are greenish grey,
but paler below, with a brown head. Adults occur from
April to September and larvae from May onwards, there
being three or more generations annually.
LIFE HISTORY
Adults occur in May and June, and from July to
September. Eggs are laid at the edge of the leaves of
birch, the larvae subsequently mining and forming
brownish, semitransparent blotches. There may be one
or several mines per leaf, the galleries often uniting and
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