Hellebore leaf miner

A leaf mining fly that became established in Britain in the 1990s, it can cause considerable disfigurement to the foliage of stinking hellebore, Helleborus foetidus.

Hellebore leaf miner

Quick facts

Common name Hellebore leaf miner
Scientific name Phytomyza hellebori
Plants affected Stinking hellebore Helleborus foetidus
Main symptoms Brownish black blotches and lines develop on the foliage during winter
Most active August to March

What is hellebore leaf miner?

Hellebore leaf miner is a small fly with larvae that tunnel inside the leaves of Helleborus foetidus.

Symptoms

  • Only Helleborus foetidus is affected by this insect
  • The mines in the leaves are initially brownish-black blotches, but later become sinuous, whitish-brown tunnels
  • In heavy attacks, most of the foliage can be disfigured by spring
  • Damage develops during late summer to early spring

Control

Although the mines can be unsightly, H. foetidus plants are not greatly harmed and so the damage can be tolerated.

Non-chemical control

  • Heavily mined leaves can be cut off and destroyed during the winter before the adult flies emerge

Chemical control

  • It is very difficult to achieve control of leaf miners with insecticides
  • If plants become extensively infested a systemic insecticide that may kill the larvae inside the leaves can be used. One systemic insecticide is available to home gardeners the neonicotinoid acetamiprid (e.g. Bug Clear Ultra)
  • Plants in flower should not be sprayed due to the danger to pollinating insects
  • Inclusion of a pesticide product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener

Download

Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)

Biology

  • This hellebore leaf mining fly was first discovered in Britain in 1999 and is now widespread in England and occurs in parts of Wales
  • Eggs are laid on the foliage and the larvae begin feeding inside the leaves during August
  • The mines are not fully developed until the new year. Pupation takes place within the leaf mines

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