Biology Reference
In-Depth Information
217
most races of this species are parthenogenetic, males
occur on some hosts in certain areas. Also, details of the
lifecycle vary according to conditions. Under glass, two
to three generations may occur annually.
DAMAGE
Infestations disfigure and weaken host plants, and often
cause premature leaf fall.
Parthenolecanium persicae
(Fabricius) (
217
)
syn.
P. crudum
(Green)
Peach scale
Infestations of this scale insect occur on various
ornamental plants, including
Citrus
, common fig (
Ficus
carica
), false acacia (
Robinia pseudoacacia
), flowering
cherry (
Prunus
), honeysuckle (
Lonicera
) and rose
(
Rosa
). In northern Europe, attacks are usually heaviest
under glass or on hosts growing against sheltered, sunny
walls. Adult female scales (5-6 mm long) are shiny
brown, with a distinct anal cleft and a slight longitudinal
keel. The nymphs are elongate-oval, yellowish brown to
brownish-orange, marked with dark brown, and rather
flat; long, straight glass-like strands of silk radiate
outwards from the body. Infested stems become coated
in scales, which often cluster closely together. The
insects excrete considerable quantities of honeydew, and
host plants are further contaminated by sooty moulds.
217
Peach scale (
Parthenolecanium persicae
).
218
Parthenolecanium pomeranicum
(Kawecki) (
218
)
Yew scale
Similar in appearance and biology to
Parthenolecanium
corni
but restricted to yew (
Taxus
). Infestations, which
occur mainly on the leaves, are unsightly, particularly
when hosts are contaminated by honeydew and sooty
moulds. The pest is also directly harmful, and heavy
attacks lead to defoliation of hedges and specimen trees.
The insect is widely distributed in mainland Europe; in
Britain it is most often noted in southern England.
218
Yew scale (
Parthenolecanium pomeranicum
).
219
Protopulvinaria pyriformis
(Cockerell) (
219
)
Pyriform scale
A pest of
Citrus
and various other plants, including bay
laurel (
Laurus nobilis
), castor oil plant (
Ricinus
communis
),
Gardenia
, oleander (
Nerium oleander
) and
spikenard (
Aralia
). Present in southern Europe,
including France, Italy, Portugal and Spain. Found in
many other warmer parts of the world, including Africa,
America and Asia.
219
Pyriform scale (
Protopulvinaria pyriformis
).
DESCRIPTION
Adult female (scale):
5-7 mm across; mainly light
brown and flattened, with a distinctly fan-shaped outline.
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