Biology Reference
In-Depth Information
325
326
325
Larval mines of poplar leaf-mining weevil (
Isochnus
sequensi
) on
Salix
.
326
Elm leaf-mining weevil (
Orchestes alni
).
327
Isochnus sequensi
(Stierlin) (
325
)
syn.
I. populi
Fabricius
Poplar leaf-mining weevil
An often common species, the larvae mining within the
leaves of poplar (
Populus
) and willow (
Salix
) to form
large, disfiguring, brownish-black blotches. Adults
(2.0-2.5 mm long) are mainly black, with a whitish
scutellum and yellowish-red antennae and legs. There is
one generation a year. Larvae occur during the summer,
and new adults (which eventually overwinter) appear in
September.
Orchestes alni
(Linnaeus) (
326-328
)
syn.
Rhynchaenus alni
(Linnaeus);
R. ferrugineus
(Marsham);
R. saltator
(Fourcroy)
Elm leaf-mining weevil
A widely distributed pest of elm (
Ulmus
); at least in
parts of mainland Europe, also associated with alder
(
Alnus
) and common hazel (
Corylus avellana
). Present
throughout much of mainland Europe, from Denmark
southwards; in the British Isles most numerous in the
southern half of England.
327
Larva of elm leaf-mining weevil (
Orchestes alni
).
328
DESCRIPTION
Adult:
2.5-3.0 mm long, with yellowish-red or red,
black-marked elytra and black legs and head; a
yellowish form also occurs.
Larva:
up to 6 mm long;
whitish to yellowish white, with a black head.
LIFE HISTORY
Adults appear in the spring to feed on the young leaves.
Eggs are laid shortly after mating, each in a main vein
on the underside of a leaf. The larvae mine within the
leaf blade, each gallery commencing as a narrow
channel that widens into a prominent brown blotch and
usually terminates at the apex of the leaf. The larvae
328
Mine of elm leaf-mining weevil (
Orchestes alni
) on
Ulmus
.
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