Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 34

49

LIFE HISTORY
Adults overwinter on bay laurel, sheltering amongst
curled or dense clusters of leaves; they also hide in leaf
litter and other debris at the base of host plants. In
spring, adults invade the young shoots to feed on the
leaves. This causes the leaf edges to curl, and provides
suitable sites within which small cluster of eggs are laid.
Nymphs feed within these protective galls, excreting
considerable quantities of honeydew; the leaf edges of
galled leaves become thickened and further curled,
changing to yellow, red or brown. Nymphs pass through
five instars before attaining the adult stage. In
favourable conditions there are two generations
annually. 49 Nymph of oak leaf sucker ( Trioza remota ).

DAMAGE
Foliage damage on heavily infested plants is
considerable and specimen plants are commonly
disfigured by the prominent galls. Infested plants,
young or old, are affected by masses of flocculent wax
produced by the nymphs; they also become sticky with
honeydew, upon which unsightly sooty moulds develop.
Young plants are most susceptible, the leaves often
turning brown and dropping prematurely; shoot death
also occurs.

50

Trioza remota Förster ( 49-50 )
syn. T. haematodes Förster
Oak leaf sucker
A generally common but minor pest of oak ( Quercus ).
Widely distributed in central and northern Europe; also
found in Japan.

50 Oak leaf sucker ( Trioza remota ) damage to leaf of Quercus .

DESCRIPTION
Adult female: fore wings 2.7-3.0 mm long, mainly
clear with yellow or brownish veins; body brownish red,
with creamy markings. Nymph: 1.8-2.0 mm long;
broad-bodied and scale-like, with a distinct fringe of
setae; light orange, with a pair of orange stripes
extending from head to tip of abdomen.

51

LIFE HISTORY
Adults occur from September to May, overwintering in
the shelter of evergreen plants and migrating to oak in
the spring. Eggs are laid on the leaves during May. The
sedentary nymphs then feed in small pits on the
underside of the leaves during the summer, moulting
into adults by about September. Adults remain on the
host plants into October but then disperse to their
overwintering sites.

51 Galls of pittosporum sucker ( Trioza vitreoradiata ) on
Pittosporum .