Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 172

387 388

387 Galls of lime leaf-roll gall midge ( Dasineura
tiliamvolvens ) on Tilia .

388 Mature galls of lime leaf-roll gall midge ( Dasineura
tiliamvolvens ) on Tilia .

389

Dasineura tiliamvolvens (Rübsaamen) ( 387-388 )
Lime leaf-roll gall midge
The striking galls of this midge occur on lime ( Tilia ),
developing on the young leaves from April or May
onwards. Each gall appears as an upward rolling of the
leaf edge, affected tissue turning dark red; galling might
extend around most if not all of the leaf margin,
producing considerable distortion; the leaf blade may
also become mottled with red (cf. galls formed by the
mite Phytoptus tetratrichus , p. 405). The galls, which
eventually turn black, enclose several whitish to orange
larvae (each up to 3 mm long). These larvae complete
their development in June; they then enter the soil
where they eventually overwinter. Adult midges appear
in late April and May, there being just one generation
annually.

389 Young galls of lime leaf gall midge ( Didymomyia tiliacea )
on Tilia .

Didymomyia tiliacea (Bremi) ( 389-390 )
syn. D. reaumuriana (Löw, F.)
Lime leaf gall midge
A local species, associated with lime ( Tilia ), forming
conspicuous, greenish-white, pustule-like galls on the
leaves, visible from above and from below. The galls,
which occur from May onwards, are about 4 mm in
diameter. Larvae, which are up to 3 mm long and white
to pale yellow, develop singly within the galls and
become fully grown by the late summer. At maturity, a
characteristic capsule containing the fully fed larva is
ejected through the underside of the gall. Individuals
overwinter on the ground within these protective
structures, adult midges appearing in the spring from
late April onwards. There are commonly up to 40 galls
on an infested leaf but, apart from possible distortion of
the leaf blade, growth is not affected.

390

390 Pupal capsule of lime leaf gall midge ( Didymomyia
tiliacea ).