Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 59

Myzaphis rosarum (Kaltenbach)
Lesser rose aphid
A widely distributed, small, elongate-oval, somewhat
flattened, green to yellowish-green aphid on wild and
cultivated rose ( Rosa ), especially climbers. The apterae
are 1.0-2.2 mm long, with long, swollen, dark-tipped
siphunculi and a long cauda (cf. Chaetosiphon
tetrarhodum , p. 58). They feed mainly along the midrib
on either side of the leaves, and are often hidden from
view amongst leaflets that are still furled. Winged
females occur during the summer; these are green or
yellowish green, with a darker mark on the abdomen.
Infestations are usually noticed only when the aphids
are unusually abundant. This species is not particularly
damaging.

LIFE HISTORY
Overwintered eggs often occur on rose bushes, although
adult aphids may survive the winter if conditions are
favourable. Substantial colonies build up during the
spring and summer, infested shoots often becoming
smothered in the aphids. In summer, winged forms
spread infestations to other rose bushes; they also
migrate to secondary hosts such as holly ( Ilex ), scabious
( Knautia and Scabiosa ) and teasel ( Dipsacus fullonum ).
Rose bushes remain liable to invasion throughout the
summer months, and new colonies are often present
throughout the autumn, until their development is
curtailed by the onset of cold weather.

DAMAGE
Infestations check the growth of buds and new shoots,
and commonly contaminate plants with sticky
honeydew upon which sooty moulds develop. Foliage
and flowers are also disfigured.

Metopolophium dirhodum (Walker) ( 112 )
Rose/grain aphid
Widely distributed on rose ( Rosa ) from autumn to late
spring, overwintering in the egg stage. Unlike the main
rose-inhabiting species Macrosiphum rosae (p. 66),
colonies do not persist on rose beyond June, the aphids
(and winged migrants) then dispersing to cereals and
grasses. Metopolophium dirhodum is rarely important
on rose. However, in some years it is present in great
profusion, and vast clouds of winged migrants are
produced; in such circumstances, rose leaves and flower
buds become covered in white, cast nymphal skins,
giving the superficial appearance of an outbreak of
disease. Apterae are elongate (2-3 mm long), and
mainly shiny yellowish green, with a darker mid-dorsal
longitudinal stripe; the antennae, legs, siphunculi and
cauda are mainly pale and relatively long. Alatae
(1.6-3.3 mm long) have a uniformly green abdomen.

11 2

11 2 Colony of rose/grain aphid ( Metopolophium dirhodum )
on Rosa .

11 3

Microlophium primulae (Theobald) ( 113 )
Colonies of this pale yellow to pale yellowish-green
aphid sometimes occur on cultivated primrose ( Primula
vulgaris ). The aphids congregate on the underside of the
leaves amongst cast nymphal skins, which commonly
remain attached to the hairy leaf surface. Although
aphid numbers are sometimes large, infested foliage is
not distorted and attacks are of little or no importance.
Apterae are 2.2-2.5 mm long, with long, tapered
siphunculi and relatively long legs; alatae are pale
yellow, with black abdominal markings.

11 3 Colony of Microlophium primulae on Primula .