Holly leaf miner

Most hollies have some leaves with evidence of a leaf mining fly, this has little impact on the plant’s growth or vigour.

Holly leaf miner (Phytomyza ilicis) on Holly (Ilex aquifolium). Credit: RHS/Entomology.

Holly leaf miner (Phytomyza ilicis) on Holly (Ilex aquifolium). Credit: RHS/Entomology.

Quick facts

Common name: Holly leaf-miner
Scientific name: Phytomyza ilicis
Plants affected: Holly (Ilex species)
Main symptoms: Yellowish-purple blotches on the upper leaf surface
Most active: All year

What is holly leaf miner?

Holly leaf miner is a small fly with larvae that cause discoloured blotches by feeding inside holly leaves.

Symptoms

Signs that holly leaf miner has been active include;

  • Yellowish-white or yellowish-purple blotches occur on the upper surface of older leaves, usually near the centre of the leaf
  • In early summer some leaves on holly trees turn yellow and fall from the tree. This is the normal shedding of old leaves and is not caused by the leaf miner

Control

Non-pesticide control

  • Although the mines may be considered unsightly, this insect can be tolerated as it has little impact on the health and vigour of a holly
  • On small specimen plants it is feasible to remove mined leaves, but not if this would result in significant defoliation as this would cause much more damage than the fly

Pesticide control

  • Insecticides are unlikely to be effective as the thick, glossy surface of holly leaves means that sprays run off the foliage and do not penetrate to where the grubs are feeding

Biology

Grubs of the holly leaf miner tunnel inside the leaves. There is one generation a year, and the adult flies lay eggs on the new foliage in May to June. When the larvae have completed their feeding in the following spring, they pupate inside the leaf mines.


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