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.

Leaf miners are a part of a healthy balanced garden ecosystem. Although the leaf mining may be considered unsightly, it is unlikely to affect the health or vigour of an established tree or shrub.

• Leaf damage from this moth is usually light and can be tolerated
• Most leaf mining species will have natural enemies including parasitoid wasps. Birds such as blue tits can sometimes open mines to consume the larvae within
• On privet hedges damage is often trimmed out
• If desired light populations 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