Biology Reference
In-Depth Information
Pontania viminalis
(Linnaeus) (
1026-1027
)
syn.
P. saliciscinereae
(Retzius);
P. vollenhoveni
(Cameron)
Willow pea-gall sawfly
A generally common, double-brooded species, forming
pea-shaped galls on the leaves of purple willow (
Salix
purpurea
) and, less commonly, crack willow
(
S. fragilis
) and osier (
S. viminalis
); the galls are pinkish
to orange-yellow, with a glabrous, somewhat warty
surface (cf.
Pontania pedunculi
). The adults (4-5 mm
long) occur in May and June, and in July and August,
the galls appearing on the underside of the leaves from
late May onwards. The larvae (up to 13 mm long) are
whitish green, each with a light greenish-brown head.
in cocoons spun amongst debris on the ground. Adults
are 3.5-4.5 mm long, and mainly black with white legs;
they occur from April to June and from July to August.
Pontania triandrae
Benson (
1024-1025
)
This species is essentially similar to
Pontania proxima
but infests the leaves of almond willow (
Salix triandra
).
The characteristically smooth, glabrous galls are at first
light green but soon become red above and pale
yellowish green below. In common with those of
P. proxima
, they are developed equally on both sides of
the leaf blade; also, there are two generations annually.
The galls are often associated with plants cultivated in
willow beds but they do not normally cause damage.
However, if present in large numbers on the top-most
growth of tall canes, the extra weight of the galls can
result in shoots becoming bent.
1024
1025
1024
Galls of
Pontania triandrae
, viewed from above.
1025
Galls of
Pontania triandrae
, viewed from below.
1026
1027
1026
Galls of willow pea-gall sawfly (
Pontania viminalis
).
1027
Larva of willow pea-gall sawfly (
Pontania viminalis
).
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