Citrus Leaf Miner
Citrus Leaf Miner is the larval state of a very small moth pest of citrus.
Usually the first sign of Citrus Leaf Miner presence is the silvery trails/mines found on the underside of young citrus leaves.
The moth is most active in the evening and early morning and eggs are only .3mm long and translucent. As such, both are not usually observed. It is usually only the larvae itself that is visible.
Damage is caused by the larvae as they mine through foliage, leaving a silvery path, usually on the underside of young 1-2cm leaves. Leaves longer than 4cm are rarely affected.
Once their final larval state is reached they roll the edge of the leaf to pupate. This causes twisted and curled leaves. Damage is most common and severe in late summer and autumn.
The full life cycle can take as little as 14 days. A female can lay more than 50 eggs during her life and as many as 20/night.
Cultural: Fertilise only when pest is scarce or absent i.e winter. Prune all new growth in late summer and autumn.
Predators: Small parasitic wasps and lacewings. Usually predators will not be enough to control populations.
Spray: Apply horticultural oil i.e white/pest oil at a ratio of 2.5-5ml to 1 litre of water. The upper and lower sides of new growth should be sprayed weekly during periods of leaf flush. This should commence as soon as leaf flush starts in summer and continue as until leaf flush finishes (usually mid autumn). This method should prevent the rapid growth of Leafminer populations.