Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 391

1061

Diplolepis rosae (Linnaeus) ( 1056-1060 )
Bedeguar gall wasp
Generally common on wild rose ( Rosa ) and sometimes
present on cultivated bushes. Present throughout
Europe; also present in North America.

DESCRIPTION
Adult: 3.5-4.5 mm long; black with a mainly red
gaster; tip of body with a distinct spine; legs partly
reddish; fore wings mainly dark, each with a darker
subapical patch. Larva: up to 6 mm long; whitish, with
a pale yellowish-brown head. Pupa: 5 mm long; white,
with purplish-white eyes.

1061 Galls of rose smooth pea-gall cynipid ( Diplolepis
eglanteriae ). LIFE HISTORY

Adult wasps emerge in the spring from May onwards,
depositing eggs in unopened rose buds. Affected tissue
begins to swell into a large, compact gall containing up
to 60 hard, wooden, cherry-stone-like cells, each
containing a single larva. The galls are surrounded by a
dense, sticky mass of branched, moss-like filaments and
measure up to 10 cm across; they change in colour from
green, through pink and bright red to reddish brown,
and darken further during the winter months. Larvae
develop throughout the summer, eventually pupating in
their cells in the following spring. Adult wasps appear
shortly afterwards. Males are unknown, reproduction
being entirely parthenogenetic. Old weather-worn galls
remain attached to host plants long after the emergence
of the adults, and are most obvious during the winter
and early spring.

1062

1062 Gall of rose spiked pea-gall cynipid ( Diplolepis nervosa ).

DAMAGE
The galls have little effect on bush growth, but are
disfiguring if present in large numbers.

Diplolepis eglanteriae (Hartig) ( 1061 )
Rose smooth pea-gall cynipid
A local but often overlooked species, forming smooth,
pea-like galls (4-5 mm in diameter) on the underside of
the leaves of rose ( Rosa ). The galls, which sometimes
bear slight surface depressions or small tubercles, also
occur occasionally on the upper surface. They appear in
July and are at first light green. They mature in
September or October, by which time they have turned
rose-red; each gall, which encloses a single larva, then
drops to the ground. The occupant pupates within its
chamber, and the adult emerges in the following May or
June. Reproduction is mainly parthenogenetic, males
being very rare. Infestations are associated mainly with
wild, rather than cultivated, bushes and are unimportant.

Diplolepis nervosa (Curtis) ( 1062 )
Rose spiked pea-gall cynipid
This generally common species is essentially similar to
Diplolepis eglanteriae but usually produces pea-like
leaf galls characterized by the presence of one or more
long, thorn-like spines. Young galls are yellowish green;
they later become flushed with pink, and finally turn
brown.