Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 72

Subfamily ERIOSOMATINAE

Periphyllus californiensis (Shinji) ( 142 )
Californian maple aphid
This North American species occurs on various species
of maple ( Acer ), including downy Japanese maple
( A. japonicum ) and smooth Japanese maple
( A. palmatum ), having been introduced into parts of
Europe, including southern England, on infested
nursery stock. The aphids (2.3-3.5 mm long) are dark
olive-green to brown; the dimorphic nymphs are light
green and similar in appearance to those of Periphyllus
testudinaceus (q.v.), but with just two series of
abdominal plates (termed spinal and marginal).

Aphids with terminal process of antennae short, eyes
reduced to three facets, siphunculi stumpy cones, pore-
like or absent, and cauda broadly rounded; body often
with groups of well-developed wax glands. Associated
with trees and shrubs, often forming galls and sometimes
migrating in summer to herbaceous plants or grasses.

Eriosoma lanigerum (Hausmann) ( 144 )
Woolly aphid
Common throughout the world on apple, including
crab-apple ( Malus ); also a pest of rosaceous orna-
mentals such as Cotoneaster , firethorn ( Pyracantha ),
hawthorn ( Crataegus ), Japanese quince ( Chaenomeles
japonica ) and Sorbus.

Periphyllus testudinaceus (Fernie) ( 143 )
This often abundant, dark brownish-green to blackish
(2.0-3.5 mm long) species infests field maple ( Acer
campestre ) and various ornamental maples. It is also
associated with horse chestnut ( Aesculus
hippocastanum ) and sycamore ( Acer pseudoplatanus ).
Heavy infestations often develop in the spring on the
young growth; later, the aphids occur abundantly
beneath the expanded leaves. The aphids produce
copious quantities of honeydew, and colonies are ant-
attended. The lifecycle follows that of Periphyllus
acericola but the dimorphic summer nymphs, which are
green and fringed with curious leaf-like hairs, aestivate
singly along the major leaf veins. Unlike those of
Periphyllus californiensis , the dimorphic nymphs
possess three series of abdominal plates (termed spinal,
pleural and marginal).

DESCRIPTION
Apterous female: 1.2-2.6 mm long; purplish brown,
covered with masses of white, mealy wax; body
with numerous wax plates; antennae short; siphunculi
pore-like.

LIFE HISTORY
Nymphs, devoid of a wax coating, overwinter in
crevices or under loose bark of suitable host plants and
become active in March or April. By the end of May
breeding colonies, now coated in masses of waxen
'wool', develop on the branches and spurs, mainly
around wounds and in splits in the bark. Breeding
continues until the autumn, with the production of a
small number of winged forms in July. Although a few
eggs may be deposited in the autumn, these fail to
develop. Thus, completion of the lifecycle is dependent
upon the production of nymphs by viviparous,
parthenogenetic females.

142

143

142 Colony of Californian maple aphid ( Periphyllus
californiensis ) on Acer .

143 Adults and nymphs of Periphyllus testudinaceus .