PEST

NAME
Leafminer (General)
Various Leafminer Species


Description of the Pest
There is a wide range of insects that have larvae, which mine leaves and these are found throughout the world. These include beetles, wasps, sawflies, moths and flies. The larvae may or may-not have legs, but are normally flattened.
These insects have a Holometabolouslife cycle, ie. When metamorphosisis observed during the pupalstage.

Typical Leafminer     

Cigar Case Bearer(Coleophora caryaefoliella) adult is a brown moth with fringed wing margins up to 9mm across. The tiny lava has a black head and feed beneath the epidermal layer of the leaf and over winters in small cigar-shaped cocoon. Commonly found on Caryaspecies.

Cineraria Leaf Miner (Chromatomia syngenesiae)is in the family Agromyzidae. This insect has a complete metamorphosis: egg, larva, pupa and adult. The adult is a small (2mm) black fly. Female adults puncture the undersides of leaves to feed on the sap. Cream coloured larvae (maggots) are miners, up to 5mm long, and their tunnels appear as a tracery of irregular white lines on the leaves, through which the larvae will be visible on the lower surfaces. The pupa is darker-coloured, barrel-shaped and up to 2.5 mm in length.

The feeding of females causes small rust-like spots to appear on the upper surface of leaves. The eggs are deposited on the undersides of the leaves. The tunnels of the larvae become wider as the insect grows and may eventually cause the infested foliage to wilt. Heavily infested plants will die; more often, the appearance of the plant is spoilt by the disfigured leaves, even though it will still produce flowers.

Cypress Moth(Recurvaria apicitripunctella) female adult is a small, yellowish with fringed wings and black markings. The larva tunnels into leaves and then ties them together with silken web, it found on Taxodium mucronatum.

Grevillea Leaf Miner(Peraglyphis atimina) a tiny larvae that eats the inner tissue of leaves and forms tunnels that expand as they grow.

The Leaf Miner (Epinotia nanana) is an olive green caterpillar with a brown head that attacks the base of the leaf and webs them together as it progresses. It is found in Tsugaspecies.

The Leaf Miner (Lithocolletis crataegella) lava forms tunnels in the inner tissue of the leaf, which becomes wider forming blisters that turn light brown. It normally occurs during late spring attacking unfolded leaves of many plant species including Crataegus.

Macadamia Leaf Miner(Arocercops chionosema) larva forms tunnels that lead to blisters in the leaves and the adult moth is brown with silver bands.

Damage Caused
There is a range of symptoms as a result of attack. Damage appears initially as tunnels on the underside of the leaves, which become broader. The leaf may form blisters and turn a rusty colour with patches visible on both sides. Continual feeding can cause the leaf to fall prematurely and give the plant an unattractive appearance. This attack is a serious problem in a forestry situation but is normally insignificant in a domestic garden. Attacks may be sporadic.

      Banksia integrifolia

Cineraria Leaf Miner
Tunnels begin to appear in early spring and continue through early summer, particularly during cooler, humid periods. The adult fly is inconspicuous and tends to go unnoticed - its presence is indicated by the appearance of the rust-like spots on the leaves as described above. Tunnels of larvae, in which the maggot pupates, may become up to 2mm wide and cover most of the surface of the foliage.

Period of Activity
The larvae are active from summer to autumn and are found from the tropics to temperate regions and generally the eggs are laid on the underside of leaves.

Susceptible Plants
There is a wide range of ornamentals and native plants that are attacked by leaf miners, including vegetables, perennials, annuals, shrubs and trees such as Nyssa sylvatica.

Aquilegiaspecies leaves are attacked by the leaf miner (Phytomyza minuscula) which causes obvious winding white tunnels across the leaf surface.

Betulaspecies are attacked by the leaf miner (Fenusa pusilla). The small black sawfly emerges from the soil primarily during spring. The small worm-like white lava feeds on the fresh new growth, and may cause substantial damage. Adults that emerge later in the season cause less destruction as the lava ignore mature leaves feeding only on new growth.

Buxusspecies are attacked by the leaf miner (Monarthropalpus buxi) that causes water soaked areas on the underside of leaves as the lava tunnels beneath the epidermal layer.

Cornusspecies are susceptible to the leaf miner (Chalepus dorsalis)yellowish lava up to 7mm long that tunnels the leaves causing blisters and the adult beetles skeletonise the underside of the leaves.

Leucanthemumand Dendranthemaspecies are attacked by the Chrysanthemum Leaf Miner(Phytomyza atricornis).

Macadamiaspecies and Stenocarpus salignusare attacked by the Macadamia Leaf Miner.

Pericallis x hybridus(Cineraria) is attacked by the Cineraria Leaf Miner (Chromatomia syngenesiae).Leafy vegetables are also susceptible, as are plants in the Asteracea family and related ornamentals such as chrysanthemums, nasturtiums, and gerberas. Sow thistle and other leafy weeds are hosts for this insect. The foliage becomes covered with unsightly, tortuous silvery lines which ultimately ruin the appearance of the plant. Heavy infestations cause wilting and death of the plants. Do not take cuttings from affected plants.

Verbenaspecies are attacked by the leaf miner (Agromyza artemisiae), which mines the leaf margins.

Cultural Control
It is difficult to control leaf miners and damaged leaves may be removed then destroyed from localised infestations.

BiologicalControl
Many leaf miners are attacked by parasitic wasps and small birds which reduces numbers.

Chemical Control
Chemical treatment includes spraying with dimethoate; note that it is advisable to treat the plants before the larvae pupate and being certain to cover the new growth avoiding reinfestation.
Note
Always read the label for registration details and direction of use prior to application of any chemicals.