Citrus leafminer

Page last updated: Thursday, 17 May 2018 - 11:41am

Citrus leafminer, Phyllocnistis citrella Stainton, is the only leafminer attacking citrus in Australia. Originating from South East Asia, citrus leafminer (actually a moth) was first found in Western Australia in 1995 and occurs in most citrus producing areas of the world.

The larvae are the damaging stage, attacking the young growth flush and causing leaves to twist and curl.

This damage is easily identified by the mines that the larvae produce in the leaves. Older trees can usually sustain damage, but young trees can be severely affected.

Damage

  • This insect attacks all citrus varieties.
  • Larvae infest the young flushing foliage, producing a snake-like 'mine' as they feed. This causes the leaves to twist and curl.
  • Larvae can also attack fruit and stems, though this is rarer.
  • Severe infestations can retard growth of young trees. Infestations on older trees (more than five years) can cause unsightly damage, but do not normally cause significant yield losses.
  • In Western Australia, attacks are most severe in late autumn peaking in April or May, depending on temperature.
  • In spring, damage is minor as the leafminer population is smaller. As a result, only a small proportion of the prolific spring flush is attacked.

Life cycle

Citrus leafminer life cycle includes egg, pupa, larva to adult
Citrus leafminer life cycle
  • Adults are about 2mm long, silvery-white in colour with wings fringed with long hairs. They are visible and are active in the morning and night.
  • Females lay eggs singly under the leaf. Females can lay up to 50 eggs. Newly emerged leaflets (10-20mm) are the preferred egg laying site.
  • After 2-10 days the larvae hatch. There are three larval stages. When they first hatch, larvae are pale-green and difficult to see. As they begin feeding, the larvae excrete their faeces into the mine forming a visible trail.
  • Larvae cannot move from leaf to leaf or from lower to upper leaf surface, but remain on the same leaf throughout their life. One o eight larval mines can be found on a single leaf.
  • When larvae complete their feeding (5-6 days in summer), they mine near the edge of the leaf causing the leaf margin to fold over. The larva moults into the fourth instar or prepupa.
  • Pupation occurs in a fold on the edge of the leaf. The pupa remains in the mine until it emerges as an adult. The pupal stage lasts six days.

Author

Sonya Broughton