Biology Reference
In-Depth Information
Phyllobius argentatus
(Linnaeus) (
348
)
Silver-green leaf weevil
A common but minor pest of various trees and shrubs,
including alder (
Alnus
), beech (
Fagus sylvatica
),
birch (
Betula
), flowering cherry (
Prunus
), hawthorn
(
Crataegus
) and
Sorbus
; sometimes also found on
conifers. Often troublesome on young ornamentals and
nursery stock. Widespread in Europe.
Phyllobius oblongus
(Linnaeus) (
350
)
Brown leaf weevil
An often abundant species, occurring throughout
Europe on various trees and shrubs, including elm
(
Ulmus
), lime (
Tilia
), maple (
Acer
), poplar (
Populus
)
and willow (
Salix
), but most often noted on rosaceous
hosts such as crab-apple (
Malus
), flowering cherry
(
Prunus
) and hawthorn (
Crataegus
); frequently a
problem on nursery trees. Adults (3.5-6.0 mm long) are
black, with reddish-brown, slightly pubescent elytra,
and brownish legs and antennae; unlike other members
of the genus, the elytra are devoid of scales.
DESCRIPTION
Adult:
4-6 mm long; body black, but appearing bright
green due to a covering of shiny, golden-green, rounded,
disc-like scales; legs and antennae light brown or
yellowish and partially clothed in golden-green scales;
femora toothed (cf.
Polydrusus formosus
, p. 166).
Phyllobius pyri
(Linnaeus) (
351
)
Common leaf weevil
Heavy infestations of this species often occur on trees
and shrubs, including alder (
Alnus
), ash (
Fraxinus
excelsior
), beech (
Fagus sylvatica
), birch (
Betula
), elm
(
Ulmus
), flowering cherry (
Prunus
), hawthorn
(
Crataegus
), horse chestnut (
Aesculus hippocastanum
)
and
Sorbus
. The weevils often occur in association with
Phyllobius argentatus
, and sometimes cause extensive
damage to the foliage and blossom of ornamentals and
nursery stock. In early summer, they show a particular
preference for nettles (
Urtica
). Adults are 5-7 mm long
and mainly black, but more or less covered with
elongate, coppery, golden or greenish-bronze scales; the
femora are distinctly toothed.
LIFE HISTORY
Adults feed in the spring and early summer on the
foliage and flowers of various trees and shrubs. In sunny
weather, they often bask openly on the leaves; in dull
conditions they tend to hide amongst folded or crinkled
foliage, often sheltering in vacated habitations of leaf-
rolling moth larvae and other leaf-deforming pests, but
they are readily detected if a branch is tapped over a
cloth or tray. Later in the season, the weevils migrate to
other hosts, including herbaceous plants. Eggs are laid
in the soil during the early summer. Larvae feed on the
roots of various herbaceous weeds and grasses. They
pupate in the spring within earthen cells, and adults
emerge a few weeks later.
Phyllobius roboretanus
Gredler (
352
)
syn.
P. parvulus
(Olivier)
This relatively small species is common on young trees,
especially oak (
Quercus
), upon which it may be found
from May onwards; also associated with nettle (
Urtica
).
Adults are 3-4 mm long, with untoothed femora and the
elytra coated in green scales; they are readily
distinguished by the black, unscaled underside of the
abdomen which bears just a few green hairs (cf.
Phyllobius viridiaeris,
p.166).
DAMAGE
Adults bite holes into the leaves and flower petals,
sometimes causing extensive damage to young trees and
shrubs; most damage is caused from April to July, but
the extent of injury varies considerably from year
to year and is not apparently related to the size of
populations invading the trees.
Phyllobius maculicornis
Germar (
349
)
Often common on young deciduous trees and shrubs,
especially beech (
Fagus sylvatica
), birch (
Betula
) and
hawthorn (
Crataegus
). This species is usually less
numerous than
Phyllobius argentatus
, but is capable of
causing extensive damage to the foliage of suitable
hosts. Both species are of similar appearance and size,
but
P. maculicornis
is distinguished by the black femora
and stouter, partly blackish antennae (club and apex of
the scape) and more prominent eyes.
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