Biology Reference
In-Depth Information
214
Lichtensia viburni
Signoret (
214-215
)
Viburnum cushion scale
A locally distributed species, occurring mainly on
European ivy (
Hedera helix
) but also associated with
Viburnum tinus
; minor infestations sometimes occur on
ornamental plants and hedges in England, Wales and
parts of mainland Europe. The female scales are 3-5 mm
long, brown and somewhat fleshy. In May, the females
mature and produce large numbers of whitish to pale
brownish-white eggs. The eggs are contained in
prominent (5-6 mm long) ovisacs, composed of sticky
masses of white waxen 'wool', which almost completely
cover the maternal scales. Eggs hatch in late June. The
emerged nymphs then attach themselves to either side of
expanded leaves to begin feeding. Development is
relatively slow, with the scales maturing in the following
spring. Adult males usually appear in late April and May.
Male tests are 2.0-2.5 mm long, white and elongate-
oval, with distinct longitudinal ridges. This pest
produces considerable quantities of honeydew upon
which disfiguring sooty moulds develop.
214
Female scale and egg mass of
Lichtensia viburni
.
215
Parthenolecanium corni
(Bouché) (
216
)
Brown scale
A generally common pest of trees and shrubs, including
ornamentals such as
Ceanothus, Cotoneaster
, crab-
apple (
Malus
),
Elaeagnus
,
Escallonia
, firethorn
(
Pyracantha
), flowering cherry (
Prunus
), flowering
currant (
Ribes
sanguineum), honeysuckle (
Lonicera
),
Japanese quince (
Chaenomeles japonica
),
Magnolia
,
rose (
Rosa
) and
Wisteria
. Present throughout Europe
and in many other parts of the world.
215
Female scales of
Lichtensia viburni
.
216
DESCRIPTION
Female scale:
4-6 mm long; more or less oval, very
convex and roughened; chestnut-brown and often shiny.
Egg:
minute, oval, whitish and shiny.
Nymph:
oval,
flat, pale greenish to orange or light brown.
LIFE HISTORY
In most situations, eggs are laid beneath the female
scales in May or June. They hatch from mid-June
onwards. First-instar nymphs then move to the young
leaves and shoots to begin feeding. Second-stage
nymphs, that are also mobile, appear in August. They
continue feeding on the young growth, but in the
autumn they migrate to the branches and twigs. Here
they settle down for the winter, gradually changing
colour from greenish to brownish. Activity is resumed
in the following spring, individuals then settling
permanently and growing rapidly. As development
continues, the body becomes increasingly hardened and
convex, to form the familiar protective scale. Although
216
Brown scale (
Parthenolecanium corni
).
Search WWH ::
Custom Search