Leaf miners GWF245
Updated January 2009
Wiggly lines or blisters on leaves are tell-tale signs of a leaf-miner attack. There are many
different species but the damage is rarely serious enough to warrant any action.
Q What are leaf miners? fly. Its larvae tunnel into turn into blotches. Unlike the
beetroot-family plants like other leaf miners there is only
A Many insect larvae produce spinach, and weeds, such as fat one generation per year. They
mines by burrowing, and feeding hen. It lays up to 20 eggs in spring overwinter in the mines, so it is
between the upper and lower leaf and early summer. The white worth picking off infested leaves
surfaces. This lets in air, so mines larvae or maggots feed for about on precious plants.
are often pale or silvery. Mines two weeks making pale leaf Lilac-leaf miner (Caloptilia
vary in shape from wiggly lines to blisters. They pupate in the soil syringella) lays eggs on the leaf
blisters according to the miner for 2-3 weeks. The pupae from undersides of lilacs, ash and
involved. Affected plants look the last generation overwinter in privet in late spring and early
bad, but the long-term damage is the soil. Like celery fly, there are summer. The caterpillars hatch
usually slight. There are up to three generations each and begin life as leaf miners,
exceptions, though eg if seedlings summer. The later ones can be blistering the leaves. As they
are affected, they can die. very numerous if the late summer grow, they feed outside the
Q Which species am I likely to weather is hot and dry. Usually leaves, inside rolled-up leaves
come across outdoors? the damage is only cosmetic and and webbing. After pupating, the
the plants recover, but you might second generation of moths
A Celery-leaf miner (Euleia have to discard some parts, like emerges in late summer. The
heraclei) often attacks celery, spinach leaves, for example. pupae from these overwinter
celeriac and parsnip leaves, and Apple-leaf-mining moth beneath trees, hedges and on
less commonly, parsley and (Lyonetia clerkella) attacks apple, garden fences.
carrots. Affected plants are cherries, birch and hawthorn trees Laburnum leaf miner
stunted and don’t crop well. The from late spring. When the eggs (Leucoptera laburnella) lays eggs
tiny, 5mm-long fly lays about 100 hatch, the caterpillars fill the on the leaf undersides of
eggs inserted into the leaf in leaves with winding mines, until laburnums in late spring and early
spring and early summer. They the fully grown green caterpillar summer. These hatch into leaf-
hatch in 1-2 weeks. After 2-3 pupates. The chrysalids are mining caterpillars that bore
weeks burrowing in the leaves the formed in the foliage in a mass of spiral mines in the leaves, until
larvae pupate. The pupae may be webbing. There may be several the whole mine is a single blotch.
in the leaf or the soil. The second generations per year. The damage A second generation emerges
generation of adults emerges 3-4 can look spectacular, but, with during late summer which feeds
weeks later, and this can be the exception of young trees, it until early autumn, when it
followed with a third generation does no real long-term damage. produces the cocoons that
in late summer. It survives the Holly-leaf miner (Phytomyza overwinter in the fallen leaves or
winter as pupae in the soil. As ilicis) can attack most hollies. The on the twigs.
the second and third generations tiny fly emerges in late spring and
overlap, attacks can be expected
Q What are the common
lays eggs in slits beneath the leaf.
at any time during the summer. greenhouse ones?
The larvae or maggots disfigure
Beet-leaf miner (Pegomya the leaves with yellow or brown A Chrysanthemum-leaf miner
hyoscyami) is a small, 6mm-long meandering mines that eventually (Chromatomyia syngenesiae), a
3mm-long fly, is a common
Q What do they look like? Q Can they be sprayed?
chrysanthemum pest also found
on related plants such as A Although the damage they A Contact insecticides containing
cinerarias, lettuce, and cause is obvious, the adults bifenthrin or pyrethrins may help
groundsel. The adult fly lays its themselves are inconspicuous control leaf miners. Don’t spray if
eggs inside the leaf. The flies, beetles or moths. Gardeners you are using biological controls.
puncture marks could be seldom notice them, and
mistaken for the early stages of identification is a job for experts.
white rust, and eggs, laid in Q What should organic growers
about 10 per cent of them, hatch use?
into larvae after a week. The Q How do I know if they
larvae produce thin mines are present? A Organic insecticides might give
wandering over the leaves. These A The mines can wander some control, if applied in the
early stages of an attack. Using
take about ten days to mature. aimlessly about the leaf, spiralling
fleece or insect-proof mesh over
Several mines together on a leaf round the leaves or look like
celery and parsley, for example,
looks like one large blotch. This blotches. The miners’ black
will keep off celery fly, as well as
resembles the damage caused by droppings can be seen in the
greenfly and carrot fly. In
chrysanthemum-blotch miner mines. When the mines are small
greenhouses, consider using a
(Trypeta zoe), this causes blister- they are hard to see, but they
like mines. Affected leaves rapidly get larger. When fully
wither and die. After pupating as developed, the whole leaf is
a white blister beneath the leaf, brown and dead. The miner can
the adult fly hatches and lays usually be seen as a dark patch in
Q Tell me about biological
about 75 eggs during its 2-3-week controls.
the mine. When you open up the
lifetime. Summer is the usual patch, it turns out to be a grub, A Greenhouse leaf miners can be
time for attacks, but in a heated caterpillar or pupa. controlled by the parasitic wasp
greenhouse they occur at any Diglyphus isaea. This wasp thrives
time. Tomato-leaf miner in summer, and can quickly
(Liriomyza bryoniae) is a tiny, Q Can they be mistaken for eliminate leaf miners in
3mm-long, black fly, similar to anything else? greenhouses or conservatories.
the chrysanthemum-leaf miner,
but pupates outside the leaf.
A Eelworms will produce Supplies can be obtained from
Biowise 01798 867574
darkened leaf areas, but there are
Defenders 01233 813121
no mines or miners.
Q Are there any others I should 0845 402 5300
be on the lookout for? Just Green 01621 785088
Q What can I do about leaf
A Imported plants, especially miners?
Scarletts 01206 240466
chrysanthemum cuttings, can
carry the South American leaf
A Discourage them by getting rid
miner (Liriomyza huidobrensis), of weeds that they feed on. Q Can they be trapped?
Compost or burn infested foliage.
American serpentine leaf miner A Sticky yellow traps used for
(Liriomyza trifolii), American Prevent further attacks by
whitefly control will catch many
vegetable-leaf miner (Liriomyza squashing the leaf miner as soon
adult greenhouse leaf-miner
Sativae) and the North American as the mines are seen. Picking off
moths and flies. They are hard to
cabbage-leaf miner (Liriomyza affected leaves and destroying
recognise, and look like tiny flies.
brassicae). None of these are them will also help. Digging the
established in the UK, and affected sites may bury any pests
overwintering in the soil, either
stringent quarantine measures
preventing them reaching the
Q Can leaf miners be avoided?
are taken to keep them from
getting into the country. surface or exposing them to birds A Sadly, they are so mobile that
and other predators. there seems to be no way to
avoid these pests.
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