Biology Reference
In-Depth Information
130
131
130
Colony of downy birch aphid (
Euceraphis punctipennis
).
131
Colony of hazel aphid (
Myzocallis coryli
).
Euceraphis betulae
(Koch) (
128-129
)
Silver birch aphid
A very common pest of silver birch (
Betula pendula
),
including cultivars such as Swedish birch (
B. pendula
'Dalecarlica'). Infestations frequently develop on trees
in gardens and nurseries. Widely distributed in Europe.
Euceraphis punctipennis
(Zetterstedt) (
130
)
Downy birch aphid
This aphid is virtually identical in appearance and habits
to the previous species but breeds on downy birch
(
Betula pubsecens
).
Myzocallis coryli
(Goeze) (
131
)
Hazel aphid
Generally abundant on both wild and cultivated hazel
(
Corylus
), and often a minor pest of nursery stock.
Eurasiatic. Present throughout Europe. Also now found
in North America and New Zealand.
DESCRIPTION
Alate female:
3-4 mm long; body elongate, mainly
light green or yellowish green and coated in a bluish-
white waxy secretion; legs and antennae very long;
siphunculi very short; cauda knobbed.
Nymph:
green
and waxy, with distinctly dark legs and siphuncular
rims.
DESCRIPTION
Alate female:
1.3-2.2 mm long; shiny, whitish to
yellowish or light green, with large red eyes; siphunculi
stumpy; cauda knob-like and projecting beyond a bilobed
subanal plate; wing veins terminate in dusky spots on the
wing margins.
Nymph:
pale, with body hairs capitate.
LIFE HISTORY
This species overwinters in the egg stage on the shoots.
The eggs hatch in the spring. Nymphs then develop on
the leaves, the first adults appearing in late May or early
June. The aphids occur on the youngest, still unfurling
leaves and on the underside of fully expanded ones, and
infestations persist throughout the spring and summer.
Adult aphids are always winged and do not aggregate,
typically occurring singly; they are also very active and
immediately drop from the foodplant if disturbed.
Nymphs either occur singly or in small groups.
LIFE HISTORY
Overwintered eggs hatch in the spring. Aphids then feed
as scattered individuals on the underside of the foliage
from May onwards. Breeding continues throughout the
summer months, all of the aphids developing into
winged forms. Sexual morphs arise in November and
oviparous females finally deposit eggs on the shoots.
DAMAGE
Foliage is not distorted but does become sticky with
honeydew; infested plants are also disfigured by sooty
moulds.
DAMAGE
Although shoots of infested plants are not distorted, the
foliate is disfigured by the accumulation of sticky
honeydew and development of sooty moulds.
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