Biology Reference
In-Depth Information
413
414
413
Galls of osier leaf-folding midge (
Rabdophaga
marginemtorquens
).
414
Larva of yew gall midge (
Taxomyia taxi
).
415
416
415
Gall of yew gall midge (
Taxomyia taxi
).
416
Old gall of yew gall midge (
Taxomyia taxi
).
Rabdophaga marginemtorquens
(Bremi) (
413
)
syn.
Rhabdophaga marginemtorquens
(Winnertz)
Osier leaf-folding midge
Leaves of osier (
Salix viminalis
) are frequently infested
by larvae of this common and widespread species.
Adults occur in the spring, and deposit eggs along the
margins of young leaves. Attacked leaves develop long,
continuous marginal folds which become yellowish
green and tinged with red; the galls enclose several
orange larvae (up to 2 mm long) (cf.
Rabdophaga
clausilia
), the position of each being disclosed by a
local swelling. Fully fed larvae vacate the galls in
August or September; they then overwinter in the soil
and pupate in the spring. The galls do not affect plant
growth, although severe infestations in nursery beds
give an impression of poor plant quality. Similar galls
are formed on osier by the mite
Aculus truncatus
(p. 418).
Taxomyia taxi
(Inchbald) (
414-416
)
Yew gall midge
A common pest of yew (
Taxus
); also associated with
cowtail pine (
Cephalotaxus harringtonia
). Present
throughout Europe.
DESCRIPTION
Adult:
3-4 mm long; yellowish orange.
Larva:
up to
3 mm long; yellowish orange, lacking a sternal spatula.
LIFE HISTORY
This species usually has a two-year lifecycle. Adult
midges occur in May and June. Eggs are deposited singly
in the terminal buds of yew trees, and hatch about one to
three weeks later. The young larvae then burrow into the
immature buds to begin feeding. Each infested bud
develops into a distinctive gall, formed from a tight
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