Biology Reference
In-Depth Information
353
354
353
Adult of
Phyllobius viridiaeris
.
354
Red palm weevil (
Rhynchophorus ferrugineus
)
.
(C. I. Carter).
Phyllobius viridiaeris
(Laicharting) (
353
)
syn.
P. pomonae
(Olivier)
A generally common weevil, sometimes causing minor
damage to the foliage of young ornamental trees and
shrubs. Adults (3.0-4.5 mm long) are black, covered
with green or yellowish-green scales both above and
below; the antennae and legs are mainly reddish and the
femora untoothed.
DAMAGE
Although adults are sometimes present in large
numbers, damage to ornamental trees and shrubs is
usually slight.
Polydrusus pterygomalis
Boheman
This local but widely distributed weevil occurs on
young trees, including hawthorn (
Crataegus
), flowering
cherry (
Prunus
), oak (
Quercus
) and willow (
Salix
),
contributing to leaf damage caused by other more
numerous leaf weevils. The adults (3-5 mm long) are
black-bodied, coated in shiny green scales, with yellow
legs and antennae; the femora are untoothed and the
head has distinctly swollen temples.
Polydrusus formosus
(Mayer)
syn.
P. sericeus
(Schaller)
Green leaf weevil
A locally common but minor pest of various trees
and shrubs, including alder (
Alnus
), birch (
Betula
),
common hazel (
Corylus avellana
), elm (
Ulmus
), poplar
(
Populus
), oak (
Quercus
) and willow (
Salix
); also
occurs on conifers. Widespread in Europe; introduced
into North America.
Rhynchophorus ferrugineus
Olivier (
354
)
Red palm weevil
This important Asiatic pest of date palm and other
Arecaceae (including many ornamental species) has
spread to various parts of the Pacific region. It has also
extended it range westwards into the Mediterranean
Basin, and has now reached parts of France, Greece,
Italy, Portugal and Spain. The very large (
c
. 40 mm
long), elongate and mainly reddish-brown adults
deposit eggs singly in cavities formed within host
plants, and the eggs hatch a few days later. Larvae (up
to 50 mm long) are yellowish-white, plump and sac-
like, with a chestnut-brown head. They feed inside the
trunk and branches of host trees, and become fully
grown in 1-3 months. Pupation then occurs in dense,
fibrous cocoons, and new adults emerge 2-3 weeks
later. Adults and larvae cause extensive damage, and
attacked trees are eventually killed. As with South
American palm borer (
Paysandisia archon
) (see p. 217),
steps are underway to prevent further spread of red palm
weevil within Europe.
DESCRIPTION
Adult:
5-8 mm long; body black, but covered with
shiny, green scales; legs brown; femora untoothed.
Furrow (strobe) on each side of the rostrum, distinct and
curved downwards posteriorly below the eye - typical
of
Polydrusus
(in
Phyllobius
the strobes are straight and
often filled with scales).
LIFE HISTORY
Adults occur during the spring and summer, feeding on
the buds, flowers and foliage of trees and shrubs. Eggs
are laid in the soil. Larvae feed on plant roots from
summer onwards; they hibernate during the winter and
pupate in the early spring.
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