Biology Reference
In-Depth Information
411
411
Gall of willow button-top midge (
Rabdophaga heterobia
).
412
412
Section through gall of willow button-top midge
(
Rabdophaga heterobia
).
Rabdophaga clausilia
(Bremi)
syn.
Rhabdophaga inchbaldiana
(Mik)
Willow leaf-folding midge
This widely distributed midge causes a discontinuous
marginal rolling of willow (
Salix
) leaves. Each roll-gall,
unlike those of
Rabdophaga marginemtorquens
(p. 188), consists of a short length of folded tissue
which encloses a single yellowish-orange larva. The
galls, which mature in the autumn, occur mainly on
white willow (
S. alba
). They are noted occasionally on
cultivated plants but damage is not important.
Rabdophaga heterobia
(Löw, F.) (
411-412
)
syn.
Rhabdophaga saligna
(Hardy)
Willow button-top midge
A widespread species, breeding in galled terminal buds,
lateral buds and male catkins of certain kinds of willow,
especially almond willow (
Salix triandra
). Adults occur
in two main generations, from late April to September,
depositing eggs on or close to the growing points.
Infested terminal buds develop into loose rosette galls,
each enclosing up to 40 tiny (
c
. 2 mm long), whitish to
orange-red larvae. When fully fed, the larvae pupate in
white cocoons formed within the gall. Adults emerge
shortly afterwards. Larvae of the second generation
induce further terminal and lateral galls. The larvae
eventually overwinter. They then pupate in the spring,
usually still within the protective remnants of the dead
rosette leaves which remain attached to host plants long
after leaf fall.
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