Holm oak leaf-mining moths

Holm oaks (Quercus ilex) are affected by several leaf mining insects. The most troublesome are two species of leaf-mining moths; Holm oak blotch leaf-miner (Phyllonorycter messaniella) and Holm oak linear leaf-miner (Ectoedemia heringiella).

Holm oak leaf miner (Phyllonorycter messaniella) on Holm oak (Quercus ilex). Credit: RHS/Entomology.

Quick facts

Common names Holm oak leaf-mining moths
Scientific names Phyllonorycter messaniella and Ectoedemia heringella
Plants affected Holm oak (Quercus ilex)
Main symptoms Brownish white blotches or wiggly linear mines in the foliage
Most active All year

What are holm oak leaf-mining moths?

Leaf-mining moths are tiny moths with caterpillars that feed inside leaves, creating discoloured blotches and meandering lines where the internal tissues have been eaten away.

Symptoms

  • Holm oak blotch leaf-miner (Phyllonorycter messaniella) causes pale brown, elongate oval discoloured areas on the upper leaf surface where caterpillars have eaten out the internal leaf tissues. The underside of these mines is whitish brown and is often torn open.
  • Holm oak linear leaf-miner (Ectoedemia heringiella), causes brown linear mines that end in a blotch. This is mainly in south-eastern England, where it was first discovered in 2002, but is becoming more widespread. As with the other leaf miner on holm oak, the tree’s appearance can be at its worst during spring.
  • On evergreen oaks, the damage from both leaf-miners can remain visible until the old leaves drop in early summer.

Control

  • There is no control available for holm oak leaf-miners, although there are several predators and parasites that can limit populations 
  • Fortunately, holm oaks tolerate the damage and continue to grow, even when heavily infested.
  • The appearance of the tree will improve in early summer, when new foliage develops and some of the old mined leaves have been shed.

Biology

  • The tiny leaf-mining moth, Phyllonorycter messaniella has three generations a year. Larvae feed within the leaves during July, October, and from November to March. When fully fed, the larvae pupate within the leaf mines. By late winter, much of the foliage on a holm oak may be affected. The tiny moth has brownish-white wings with a span of almost 8mm.
  • Mines caused by Ectoedemia heringella develop during spring and are fully formed by the end of May. The adult moth has a wingspan of 5-6 mm and the forewings are white and black in colour.

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