Agriculture Reference
In-Depth Information
having been introduced into glasshouses from
abroad, usually on chrysanthemum plants. In
parts of southern Europe, this pest is also now
established on outdoor plants. The characteristic
leaf mines arise from close to the mid-rib or ma-
jor veins; each then progresses as a tortuous gal-
lery that often turns tightly back upon itself, and
thus appears broad and blotch-like. Pupation
occurs in the mine or in the soil, in a yellowish-
brown or reddish-brown puparium. There are
several generations annually. Feeding punctures
formed in leaves by adult females are often very
numerous. Larvae are up to 3.3 mm long; each
posterior spiracle bears an arc of six to nine small
pores (cf.
Liriomyza trifolii,
below).
on relatively mature plants; attacks also occur on
various ornamentals. The mines often follow the
major veins of the leaves and are usually much
branched, with short lateral galleries extending
into the lamina; mines are rarely numerous and
damage caused is of little or no importance. The
posterior spiracles of the larvae each have 10-12
pores.
Liriomyza trifolii
(Burgess)
larva -
American serpentine leaf miner
This mainly North American species is fre-
quently introduced into Europe, especially on
chrysanthemum cuttings; infestations may then
develop on glasshouse-grown crops such as
celery, cucumber, lettuce, tomato and various
ornamentals. Growth of heavily infested plants is
checked, affecting both crop yields and quality;
host plants are also disfigured by adult feeding
and egg-laying punctures. Larval mines are long,
contorted and whitish, and each contains an ir-
regular line of dark frass. Pupation occurs in the
soil (cf. chrysanthemum leaf miner,
Phytomyza
syngenesiae,
p. 192). Infestations build up rapidly
and the pest breeds continuously whilst condi-
tions remain favourable. During the summer,
infestations may spread to outdoor plants, in-
cluding
Vicia
bean and weeds such as
Senecio
jacobaea
and
Solanum dulcamara.
Adults (wings
1.2-1.5 mm long) are greyish-black with a mainly
yellow head and bright yellow scutellum and
antennae. Larvae are 2 mm long, yellow to
orange-yellow, and the posterior spiracles each
3-pored (cf.
Liriomyza huidobrensis,
p. 188; cf.
Phytomyza
spp., p. 191
et seq.).
Liriomyza orbona
(Meigen)
This widely distributed species is associated with
Bellis perennis
(Asteraceae) but also breeds on
certain members of the Poaceae, including win-
ter barley. The larvae form rather broad, whitish
leaf mines. Adults (wings 1.7-2.6 mm long) are
black, with the scutellum, halteres and knees yel-
low. They occur in May and June; the yellow-
coloured larvae feed in June and July.
Liriomyza pisivora
Hering
larva =
A pea leaf miner
This species is very similar to
Liriomyza congesta
(p. 188) but adults are darker, the yellow colora-
tion on the abdomen being far less extensive.
Infestations also occur on the leaves of pea and
Vicia
bean but the mines are usually restricted to
the lower surface, with the frass deposited in
greenish-black bands. Also, the feeding galleries
are relatively superficial and of little or no signifi-
cance. Unlike
L. congesta,
with which this spe-
cies was once confused, the posterior spiracles
of the larvae are each 7-8-pored. Mines of
Phytomyza horticola
(p. 193) may also occur on
the lower surface of pea leaves but they are
lighter in colour and much broader.
Napomyza carotae
Spencer
larva
-
Carrot miner
This species is a minor pest of carrot, the larvae
feeding in the leaves and the roots. Leaf mines
are of little or no consequence. However, mined
tap roots may become malformed; attacks are of
greatest importance on early crops. Although
larval damage tends to be restricted to the upper-
most part of the root and is relatively superficial,
Liriomyza strigata
(Meigen)
Larvae of this very polyphagous species often
mine the leaves of beet, lettuce and pea, usually
