Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 93

Family DIASPIDIDAE (armoured scales)

LIFE HISTORY
This species is favoured by stable, hot and dry
conditions. The adult females are viviparous, and give
birth to up to 150 nymphs over a period of about two
weeks. The first-instar nymphs invade the stems, but
will also settle on the foliage and elsewhere.
Development to adulthood involves three nymphal
stages and takes from 1 to 2 months. There are several
overlapping generations annually, all stages often
occurring together.

Body of female protected by a hard, scale-like covering
(commonly called a 'scale', but also termed a 'test'),
formed from wax and cast nymphal skins. The male
pupal covering is also termed a 'test'. Owing to the
mobility, first-instar nymphs are often known as
'crawlers'.

Abgrallaspis cyanophylli (Signoret)
A tropical, polyphagous species. Often established as a
persistent greenhouse pest in temperate regions,
including northern Europe where it is most often noted
on cacti; infestations also occur on orchids and palms.
The female tests are elongate-oval, 1-3 mm long, and
mainly yellow to light brown.

DAMAGE
Attacked plants are weakened. Infested branches
develop distinct lesions and become desiccated, the
leaves turning yellow and falling off. Californian red
scales often occur amongst colonies of citrus mussel
scale ( Lepidosaphes beckii ) (p. 105).

Aonidiella aurantii (Maskell)
California red scale
A pest in citrus orchards in various parts of the
Mediterranean basin. Also present on various
ornamental hosts, including rose ( Rosa ). In cooler
regions, sometimes found on greenhouse plants.
Widely distributed in tropical and subtropical parts of
the world.

Aspidiotus nerii Bouché ( 194 )
Oleander scale
This widely distributed scale insect is a common
greenhouse pest in northern Europe, infesting various
ornamentals such as Acacia, Asparagus plumosus ,
azalea ( Rhododendron ), Cyclamen, Dracaena , oleander
( Nerium oleander ) and palms. In favourable districts,
infestations also occur outdoors on hosts such as
Japanese laurel ( Aucuba japonica ); in mainland Europe,
the pest is often present on decorative container-grown
and open-bedded oleanders. The female tests are flat,
rounded (1-2 mm across) and whitish, with a central
yellow spot; male tests are similar but smaller. The pest
often occurs on the stems of host plants but is usually
most abundant on the leaves. It occurs throughout
southern Europe, North Africa, the United States of
America and Australia, but the exact distribution and
host range are uncertain owing to frequent confusion
with the closely related species Aspidiotus hederae .

DESCRIPTION
Female test: 1.5-2.0 mm across; circular, waxy and
transparent. Adult female: broadly kidney-shaped, with
the abdominal lobes extending back on either side of the
pygidium; brownish red and clearly visible through the
covering test. Male test: 1.2 mm long; oval and dark
reddish brown. Adult male: 1 mm long; yellowish;
winged. First-instar nymph: elongate-oval, reddish
brown.

194

194 Colony of oleander scale ( Aspidiotus nerii ) on Nerium .