Lilac leaf mining moth

The caterpillars of lilac leaf mining moth feed within the leaves of lilac, privet and ash. This results in brown blotches on the leaves, the leaves then become rolled up from the tip.

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Lilac leaf-mining moth

Quick facts

Common name: Lilac leaf-mining moth
Latin name: Caloptilia syringella
Plants affected: Lilac (Syringa), privet (Ligustrum) and ash (Fraxinus)
Main symptoms: Brown blotches and curled leaves.
Caused by: Caterpillar of a moth
Timing: June to September

What is lilac leaf mining moth?

Adult lilac leaf mining moths have brindled white and brown forewings and the wingspan is 10-13mm. The caterpillars feed within the leaves of host plants and are greenish white and up to 7mm long when fully grown.
Images of the adult can be found on the UK moths website (external link)

Symptoms

The larvae initially cause a large blotch mine which soon goes brown and shrivels. Each mine is occupied by several caterpillars which later leave the mine and cause the leaf to become rolled up from the tip. The leaf roll is held in position by silken threads and the caterpillars complete their feeding inside. The caterpillars pupate in silken cocoons spun on the underside of the leaf and the second generation overwinter as pupae. This moth is part of the natural biodiversity the host plants can support. 

There are two generations a year with leaf symptoms occurring in June and August to September.

Control

Leaf damage from this moth is usually light and can be tolerated. Although the leaf mining may be considered unsightly, it is unlikely to affect the health or vigour of an established tree or shrub. Leaf miners can be part of a healthy balanced garden, most species will have natural enemies including parasitoid wasps. Birds such as blue tits can sometimes open mines to consume the larvae within.

If desired light infestations on lilac trees can be dealt with by picking off and disposing of mined or rolled leaves, this can however, cause more damage than the leaf miner. On privet hedges damage is often trimmed out.

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