Biology Reference
In-Depth Information
Tetranychus urticae
Koch (
1135-1136
)
Two-spotted spider mite
An often abundant pest of greenhouse and outdoor
plants, including ornamentals such as azalea
(
Rhododendron
), buddleia (
Buddleja
), broom (
Cytisus
),
busy lizzie (
Impatiens
), calla lily (
Zantedeschia
aethiopica
),
Ceanothus, Chrysanthemum, Dahlia
,
diviner's sage (
Salvia divinorum
),
Freesia, Fuchsia,
Hippeastrum, Hydrangea
, Mexican orange (
Choisya
ternata
), morning glory (
Ipomoea
), mulberry (
Morus
),
passion flower (
Passiflora
),
Phormium tenax
, poinsettia
(
Euphorbia pulcherrima
), primrose (
Primula vulgaris
)
and rose (
Rosa
). Cosmopolitan. Present throughout
Europe.
the overwintering eggs are reddish-orange and are
usually found between bud scales or in other sheltered
positions on the bark. The mites are small (0.2-0.4 mm
long), greenish or reddish, with blackish markings, and
relatively flat-bodied.
Stigmaeopsis celarius
Banks
syn.
Schizotetranychus celarius
(Banks)
Bamboo mite
A widely distributed oriental pest of bamboo (e.g.
Phyllostachys
). Now present in many parts of the world,
including Australasia, Europe (e.g. Belgium, Britain,
France, Italy and the Netherlands) and the USA.
Bamboo mite is considered a complex of several social
species, including
Stigmaeopsis nanjingensis
which has
now become well established in northern Italy.
DESCRIPTION
Adult female
: 0.5-0.6 mm long; pale yellowish or
greenish, with two dark patches on the body
(overwintering form orange); body oval, with
moderately long dorsal setae; striae on the hysterosoma
form a diamond-shaped pattern.
Adult male:
similar to
female but body smaller, narrower and more pointed.
Egg:
0.13 mm across; globular and translucent.
Larva:
light green, with darker markings; 6-legged.
Nymph:
light green, with darker markings; 8-legged.
DESCRIPTION
Adult:
0.4-0.6 mm long; whitish to translucent.
Egg:
0.1 mm across; spherical.
LIFE HISTORY
Overwintered adult females commence egg laying in
the early spring, each initiating a small, discrete colony
beneath a densely woven silken web (often described as
a 'nest') on the underside of a young leaf. Mites exhibit
social behaviour, and typically defaecate at one and the
same point at the periphery of the communal web;
adults also demonstrate parental care, defending their
nests against predators. Breeding continues throughout
the summer and autumn (although interrupted in hot
conditions by a period of aestivation), with a succession
of overlapping generations.
LIFE HISTORY
Female mites overwinter amongst debris, in dry
crevices in the soil and in other suitable shelter, often
clustering in cracks in greenhouse structures, stakes and
DAMAGE
Infested leaves develop distinct whitish or yellowish-
white blotches on the upper surface, each coinciding
with the presence below of a mite colony. Attacked
leaves may also become pallid, and flecked with silvery
white where the contents of individual plant cells have
been removed. Photosynthetic activity is impaired, and
leaves may be shed prematurely.
1135
1135
Two-spotted spider mite (
Tetranychus urticae
) damage
to leaves of
Choisya
.
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