Biology Reference
In-Depth Information
139
Chaitophorus niger
Mordvilko (
139
)
Although local and generally uncommon, colonies of
this species are sometimes found on ornamental willow
trees, including crack willow (
Salix fragilis
), purple
willow (
S. purpurea
), weeping willow (
S. vitellina
var
.
pendula
) and white willow (
S. alba
). The aphids
(2.0-2.2 mm long) are distinguished by their overall
dark appearance, the tergites forming a solid black
carapace.
Chaitophorus saliceti
(Schrank) (
140
)
This local species occurs on broad-leaved willows,
including common sallow (
Salix atrocinerea
), eared
willow (
S. aurita
) and grey willow (
S. cinerea
), and is
sometimes found on nursery trees. Individuals are
slightly larger and also darker than those of
Chaitophorus capreae
but distinguishable with
certainly only by microscopic examination.
139
Colony of
Chaitophorus niger
on
Salix
.
140
Periphyllus acericola
(Walker) (
141
)
A generally common species on sycamore (
Acer
pseudoplatanus
), infesting both young and mature trees.
Widely distributed in Europe.
DESCRIPTION
Apterous female:
3-4 mm long; body light green, oval
and hairy; siphunculi stumpy and tapered; cauda
broadly rounded.
Nymph:
light green, with long body
hairs.
Dimorphic summer nymph:
pale yellow, with
long body hairs.
Alate:
3.0-3.5 mm long; dark-bodied.
140
Colony of
Chaitophorus salicti
on
Salix
.
LIFE HISTORY
In the spring, colonies of aphids develop on the
underside of expanding sycamore leaves. Nymphs of
the first generation usually cluster along the major veins
towards the leaf base; later, colonies (including winged
forms) also develop on the new shoots. The colonies die
out in summer, and the species survives by aestivating
as first-instar nymphs (dimorphic summer nymphs),
which cluster together (cf.
Periphyllus testudinaceus
,
p. 80) beneath fully expanded leaves. Activity is
resumed in the autumn, and is completed with the
production of sexual forms and the deposition of winter
eggs.
141
DAMAGE
Infestations have little effect on tree growth, but spring
colonies may be of minor significance on nursery trees.
141
Dimorphic summer nymphs of
Periphyllus acericola
.
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