Citrus leafminer

Page last updated: Monday, 20 July 2020 - 10:26am

Please note: This content may be out of date and is currently under review.

Monitoring and control

Monitoring

  • Monitor production of significant growth flushes (more than 25% of trees flushing) on trees less than five years old. Examine at least 20 advanced shoots (those that have emerged earlier than most of the other foliage).
  • Action needs to be taken if 10% of the more advanced flushes are infested by citrus leaf miner.

Sprays and cultural control

  • Insecticidal control is difficult because the larvae are shielded within their mines. The pupal stage is also protected by the rolled leaf margin.
  • Horticultural oil sprays reduce numbers by reducing egg lay. The tiny moths avoid surfaces sprayed with oil, so sprays should be applied before too many eggs have been laid.
  • Two or more sprays may be required when new leaves are produced over an extended period.
  • New growth should be protected as soon as it has formed. Once leaves have hardened, they are resistant to leafminer attack.

There are several ways to reduce infestations by limiting production of new leaves when leafminer numbers are highest:

  • Prune growth flushes.
  • Fertilise in late winter to promote strong spring growth when the leafminer is rarer.
  • Do not overwater or overfertilise in late summer and autumn.

Biological control

Citrus leafminer parasite is a small wasp
 The wasp Semielacher petiola is a wasp attacking citrus leafminer larvae

Parasites

  • Three of the most effective parasites in Asia (Citrostichus phyllocnistoides, Cirrospilus quadristriatus and Ageniaspis citricola) were introduced into Queensland in the 1990s. These were then released into Western Australia from Queensland. Only one, Cirrospilus quadristriatus, appears to have established in southern WA.
  • A native wasp, Semielacher petiolatus, is also found in WA. Both species attack the larva, leaving distinct pupal cases.
  • Parasitism levels are low – usually less than 5% of all larvae appear to be attacked in WA. In Queensland the introduced wasps can parasitise up to 90% of citrus leafminer larvae.

Predators

  • Generalist predators feed on citrus leafminer. These include green and brown lacewings.

Author

Sonya Broughton