Biology Reference
In-Depth Information
Tortrix viridana (Linnaeus) ( 705-706 )
Green oak tortrix moth
An important, and sometimes abundant, pest of oak
( Quercus ) trees, especially English oak ( Q. robur ).
Although primarily a forest pest, damage is also caused
to trees in parks, gardens and nurseries. Widely
distributed in Europe; also present in North Africa and
parts of Asia.
LIFE HISTORY
Adults are most numerous in June and July, and are
most abundant in oak woodlands. They rest on host
trees during the daytime but are readily disturbed. Eggs
are laid in pairs on the bark, usually close to the leaf
bases and where the shoots and small branches divide.
They hatch in the following spring at about bud-burst.
The larvae feed from late April to June, at first entering
the opening buds but later inhabiting rolled or folded
leaves. Pupation usually occurs in a folded leaf on the
host tree, but larvae also descend on a silken thread and
pupate on underlying plants. When larvae are present in
large numbers they defoliate trees before becoming
fully fed; in such circumstances they larvae might attack
the foliage of other trees, shrubs and underlying
herbage.
DESCRIPTION
Adult: 17-24 mm wingspan; head, thorax and fore
wings light green; hind wings light grey. Egg: flat and
oval, pale yellow to brownish-orange. Larva: up to
18 mm long; greenish grey to light olive-green, with
prominent blackish-brown or black pinacula; head
blackish brown to black; prothoracic plate greenish
brown to greyish, marked with blackish brown, often
edged anteriorly with white and with a pale median line;
anal plate green or black; anal comb with eight prongs;
thoracic legs black. Pupa: 10-12 mm long; brownish
black to black.
DAMAGE
Larval defoliation is redressed by the appearance of new
leaves on Lammas shoots which develop in the summer.
704
703
703 Larva of Tortricodes alternella .
704 Adult of Tortricodes alternella .
705
706
705 Female green oak tortrix moth ( Tortrix viridana ).
706 Larva of green oak tortrix moth ( Tortrix viridana ).
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