Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 114

Thrips fuscipennis Haliday ( 239 )
syn. T. menyanthidis Bagnell
Rose thrips
A common outdoor and greenhouse pest of various
flowering plants, including rose ( Rosa ) and many other
ornamentals; infestations also occur on the young leaves
of various trees. Widespread in Europe.

Thrips simplex (Morison)
syn. Taeniothrips gladioli Moulton & Steinweden
Gladiolus thrips
An important pest of greenhouse-grown Gladiolus and
to a lesser extent Crocus ; less often, Freesia, Iris and
lilies are also attacked. Probably introduced into
northern Europe from southern Africa.

DESCRIPTION
Adult female: 1.2-1.6 mm long; yellowish brown to
dark brown; legs brown; fore wings dark greyish brown,
paler basally; antennae 7-segmented; comb of setae on
hind margin of the eighth abdominal tergite incomplete
centrally. Nymph: white to pale yellow.

DESCRIPTION
Adult: 1.5 mm long; dark brown; antennae 8-segmented
and mainly dark, with the third and basal part of the
fourth and fifth segments pale; fore wings brown but
pale basally; legs dark brown, with paler tibial apices
and tarsi. Nymph: yellow to orange.

LIFE HISTORY
Outdoors, adult females hibernate and become active
in the spring, depositing eggs from May onwards.
Nymphs then occur on host plants from May to August
or September and males from June to October, with up
to four generations annually. In greenhouses, there are a
larger number of generations; however, even under
heated conditions, there is an obligatory period of
diapause from November onwards, with adult females
sheltering in cracks and crevices, in debris or in the soil;
the thrips reappear in the late winter or early spring, and
eggs are deposited from late February onwards.

LIFE HISTORY
In northern Europe, this species generally survives the
winter between the scales of stored corms where, if
temperatures remain above 10ºC, breeding continues
unabated. In the spring, when corms are planted, the
thrips will be carried upwards on the enlarging stems
and leaves; subsequently, they may also invade the
developing flowers. Gladioli growing outdoors are
sometimes infested during the summer, particularly in
hot, dry conditions.

DAMAGE
Crocus: yellowish-brown areas develop beneath the
skin of stored corms; new growth from damaged corms
is poor and creamy coloured rather than white.
Gladiolus: infested corms develop rough, greyish-
brown surface patches; infestations on developing
plants produce yellowish or silvery streaks on the
foliage and stems, which may subsequently turn brown.
When feeding extends to the flowers, invaded petals
develop silvery flecks; if attacks are severe, the petals
may also turn brown and die.

DAMAGE
Infested tissue becomes discoloured and distorted; on
rose, attacks on the developing flowers lead to
malformed, brown-streaked petals.

239

239 Rose thrips ( Thrips fuscipennis ) damage to foliage of
Ostrya .