Biology Reference
In-Depth Information
Pinnaspis aspidistrae
(Signoret)
Fern scale
Infestations of this cosmopolitan scale occur commonly
on the stems and fronds of greenhouse-grown
Aspidistra
, ferns and palms, causing discoloration of
foliage. Female tests are 2.5-3.0 mm long, reddish
brown and mussel-shaped. Male tests are
c
. 1 mm long,
white, ribbed and elongate; heavily infested foliage
often appears white.
NOTE
Two closely related species, the yellow plum scale
(
Quadraspidiotus ostraeformis
) and the yellow pear
scale (
Q. pyri
) - both with a more northerly distribution
- also occur on ornamental trees and shrubs (especially
Rosaceae) but are of only minor significance. Unlike
San José scale, their lifecycles include an egg stage and
they have just one generation each year.
Unaspis euonymi
(Comstock) (
206-207
)
Euonymus scale
A local pest of spindle (
Euonymus
), especially Japanese
spindle (
E. japonica
). Widely distributed in southern
Europe; also found further north, including coastal areas
in southern England.
Quadraspidiotus perniciosus
(Comstock)
syn.
Diaspidiotus perniciosus
(Comstock)
San José scale
An extremely polyphagous pest of trees and shrubs,
including alder (
Alnus
), ash (
Fraxinus excelsior
), beech
(
Fagus sylvatica
), birch (
Betula
), elm (
Ulmus
),
Eucalyptus
, false acacia (
Robinia pseudoacacia
),
hornbeam (
Carpinus betulus
), lime (
Tilia
), maple
(
Acer
), poplar (
Populus
),
Sorbus
, walnut (
Juglans
) and
willow (
Salix
). Originally found in Asia but now well
established in many other warmer parts of the world,
including southern Europe. The pest is very destructive,
the adults and nymphs imbibing considerable quantities
of sap and seriously weakening their hosts. Infestations
result in die-back and, often, cause death of plants. The
area around feeding sites on leaves and other green
tissue frequently turns red. The female tests (
c
. 2 mm
diameter) are yellowish, flattened and circular, with a
slightly raised eccentric nipple; male tests are smaller
and elliptical (1.0
DESCRIPTION
Female test:
2-3 mm long; brown and mussel-shaped to
oyster-shaped.
Male test:
2.0-2.5 mm long; pale yellow
to white and elongate, with three longitudinal ridges.
LIFE HISTORY
There are two generations annually, with eggs hatching
and first-instar nymphs swarming on host plants in June
and in early September. The nymphs eventually settle
down to feed on the foliage and stems of host plants.
Male tests are very obvious, and greatly outnumber
those of females.
0.5 mm). The pest is viviparous, the
mature females producing nymphs instead of eggs.
There are usually 2-3 generations annually in southern
Europe. The pest overwinters in the nymphal stage.
×
DAMAGE
Attacks cause leaf discoloration and lack of vigour;
heavy infestations cause severe decline and, eventually,
death of plants.
206
207
206
Colony of euonymus scale (
Unaspis euonymi
).
207
Euonymus scale (
Unaspis euonymi
) damage to leaves of
Euonymus
.
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