Biology Reference
In-Depth Information
LIFE HISTORY
Clusters of overwintering eggs occur on the lower
portions of rose stems, and these commonly attract
attention when bushes are pruned during the winter or
early spring. The eggs hatch in the early spring. Nymphs
then migrate to the underground parts of the stems to
begin feeding. Ant-attended colonies develop during the
spring and summer on the superficial roots and stem
bases, and these are often protected by ant-constructed
earthen shelters. In summer, winged forms spread
infestations to other rose bushes. Aphid numbers
decline in the autumn, when eggs are deposited.
LIFE HISTORY
Overwintered eggs hatch in the early spring, and
colonies of wingless aphids then develop in rows along
the needles. Colonies persist throughout the summer
and autumn, and are often attended by ants. Winged
forms are produced from May to September. Sexual
forms, including winged males, occur in the late autumn
and early winter, prior to the deposition of winter eggs.
Under favourable conditions colonies of live aphids also
survive the winter.
DAMAGE
Infested needles often turn yellow and drop
prematurely; this affects the vigour of young plants, and
reduces shoot and needle length in the following season.
DAMAGE
The growth of infested bushes may be checked, and
persistent infestations eventually cause the death of
plants.
Trama troglodytes
von Heyden
Jerusalem artichoke tuber aphid
Infestations of this large, entirely parthenogenetic aphid
sometimes occur on the roots of cultivated Asteraceae,
including
Arnica
,
Chrysanthemum maximum
,
Michaelmas daisy (
Aster
), sneezewort (
Helenium
) and
sunflower (
Helianthus annuus
); they also occur on
weeds such as dandelion (
Taraxacum officinale
) and
sow-thistle (
Sonchus
). Colonies are ant-attended and
occur on the roots throughout the year. Winged forms
appear during the summer months and then disperse to
new hosts. The aphids reduce the vigour of infested
plants and, particularly in dry conditions, cause plants to
wilt. Adults (3-4 mm long) are white, and lack
siphunculi; characteristically, if disturbed, they vibrate
their long hind tibiae.
Schizolachnus pineti
(Fabricius) (
172
)
Grey pine-needle aphid
Generally common on young pine (
Pinus
) trees,
especially Austrian pine (
P. nigra
var.
nigra
), beach pine
(
P. contorta
) and Scots pine (
P. sylvestris
). Widespread
throughout Europe.
DESCRIPTION
Apterous female:
1.2-3.0 mm long; body broadly oval,
dark greyish green, covered with long, fine hairs and
coated in white, mealy wax; siphunculi reduced to small
cones.
Alate:
2-3 mm long; greyish green.
172
173
172
Colony of grey pine needle aphid (
Schizolachnus pineti
)
on
Pinus
.
173
Colony of large willow aphid (
Tuberolachnus salignus
) on
Salix viminalis
.
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