Pyracantha leaf-mining moth

First discovered in Britain 1989, this leaf-mining moth has become widespread in British gardens.

Pyracantha leaf-mining moth

Pyracantha leaf-mining moth

Quick facts

Common name Pyracantha leaf-mining moth
Scientific name Phyllonorycter leucographella
Plants affected Mainly Pyracantha (firethorn)
Main cause Caterpillars of the moth feed inside the leaves, causing distinctive oval-shaped mines
Timing Mainly January-March

What is pyracantha leaf-mining moth?

This moth was discovered new to Britain in Essex in 1989 but has now spread throughout England and into Scotland. The wings of this small moth are bronze, with white markings. The moth's caterpillars feed inside the foliage of Pyracantha, where they cause a distinctive silvery white discoloration on the upper leaf surface.

 

Symptoms

The leaf mines cause by this moth can be seen on Pyracantha during the summer but they are much more frequent during the early months of the year. The caterpillar initially feeds by making a linear mine along the central leaf vein. Later the mine broadens until there is an oval silvery white area that occupies most or all of the upper leaf surface. When the caterpillar has completed its feeding, it causes the leaf to fold upwards, and the mine becomes less visible.

In some years, a high proportion of the leaves will have mines in them during January-March. This can give the plant an unhealthy appearance but this moth has little impact on the plant's growth, its ability to produce flowers and berries, or its long-term health. The old mined leaves may drop off in spring but new growth will restore the plant's appearance.

Control

Although leaf mining damage may be considered unsightly, it is unlikely to affect the health or vigour of an established tree or shrub. In addition many leaf miners have parasites and predators which may be killed by spraying leading to a resurgence of the leaf miner or other pests.

There are no insecticides that are suitable for controlling leaf mining insects in home gardens.

Biology

The moth lays eggs on the foliage and after hatching the larvae bore into the leaves where they feed on the internal tissues. This pest has up to three generations per year so is active during summer, but it is the late winter generation that is by far the more abundant. When the caterpillar has completed its feeding it spins silk webbing within its mine which contracts, causing mined leaves to fold upwards, with the insect pupating within the folded leaf. Although Pyracantha is the principal host plant for this moth, it can also develop during the summer in the foliage of apple, hawthorn, mountain ash and whitebeam. It is not a significant problem on these other host plants.


Gardeners' calendar

Advice from the RHS

Find out what to do this month with our gardeners' calendar

Advice from the RHS

Did you find the advice you needed?

RHS members can get exclusive individual advice from the RHS Gardening Advice team.

Join the RHS now

Get involved

We're a UK charity established to share the best in gardening. We want to enrich everyone's life through plants, and make the UK a greener and more beautiful place.