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In-Depth Information
Chromatomyia syngenesiae Hardy ( 437-439 )
syn. Phytomyza syngenesiae (Hardy)
larva
LIFE HISTORY
Eggs are laid mainly on the upper surface of the leaves
of host plants, particularly where foliage is shaded.
They hatch in 3-6 days and larvae then mine the leaves,
each forming a long white to brownish, serpentine
gallery on the upper side, within which grains of black
frass are distributed at irregular intervals. The larvae are
fully fed in about 7-10 days; they then burrow through
the leaf to the lower surface before pupating, with the
anterior spiracles of the puparium protruding through
the lower epidermis: cf. Chromatomyia horticola
(p. 199) and Liriomyza trifolii (p. 201). Adults emerge
in 9-12 days at normal greenhouse temperatures. In
common with other agromyzids, the adults feed on host
leaves by inserting their ovipositor into the leaf tissue
and then imbibing the exuded sap; the flies are also
relatively inactive, usually making only short, jerky
flights. Under protection there are several generations
each year, and breeding is continuous whilst conditions
remain favourable. Outdoors, where development may
be protracted, there are normally two generations
annually, adults occurring in May or June and again in
late July and August; the winter is passed in the pupal
stage. During the summer, greenhouses may be invaded
by flies which emerge from wild hosts, such as
groundsel ( Senecio vulgaris ) and sow-thistles
( Sonchus ), or from cultivated garden plants such as
outdoor chrysanthemums.
a chrysanthemum leaf miner
A generally abundant pest of greenhouse-grown
ornamentals, including Chrysanthemum , Cineraria , pot
marigold ( Calendula officinalis ) and sunflower
( Helianthus annuus ). Widespread in Europe; serious
infestations have also occurred in Australasia and in
North America.
=
DESCRIPTION
Adult: wings 2.2-2.6 mm long; greyish black, with pale
yellow markings on the head and sides; legs mainly
black, with yellow knees; costa reaching vein R4
5,
at apex of wing (cf. Liriomyza trifolii , p. 201). Egg:
0.35
+
0.15 mm; oval, white and shiny. Larva: up to
3.5 mm long; greenish white. Puparium: yellowish
brown to dark brown; oval but rather flattened.
×
437
DAMAGE
Foliage is disfigured by the relatively large, wavy-edged
(cf. Liriomyza trifolii , p. 201) adult feeding and egg-
laying punctures; leaves of some hosts also develop
wart-like wounds. Larval mines, which may be
extensive, spoil the appearance of ornamental plants;
437 Adult of Chromatomyia syngenesiae .
438
439
438 Puparium of Chromatomyia syngenesiae projecting from
underside of leaf of Chrysanthemum .
439 Mines of Chromatomyia syngenesiae in leaf of
Chrysanthemum .
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