Many gardeners are seeing what they call strange growths among their citrus foliage. Leaves are crinkled, twisted and in some instances almost transparent. It is always on the new growths and it makes the trees look horrible.
If you look really close among those crinkled and twisted portions, you are also likely seeing white to transparent tunnels of the citrus leaf miners. This is an insect that begins its attack on your trees as a moth laying eggs on the new leaves. Hardly anyone sees the moths but they do notice the soon to occur damage.
When the eggs hatch, larvae enter the leaves and begin to tunnel between the leaf surfaces. This is what produces the transparent areas and causes the crinkling and curling. Eventually the larvae mature and pupate to restart the life cycle. These insects are only active in affecting the new growths. A flush of new leaves can be produced at anytime but normally it occurs in spring, summer and very early fall. This is when you need to protect your trees from the citrus leaf miner.
Control can consist of applying either a horticultural oil or natural spinosad containing insecticide. These products are available from your local garden center. The later is usually only available at independent garden centers and listed for caterpillar control. Your garden center expert can help you select the right product with the proper label.
Now here is the trick to catch these insects feeding. Apply either insecticide as labeled at the beginning of each flush of new growth. This is when the new leaves are starting to form and when citrus leaf miner moths lay their eggs that hatch into larvae to tunnel within the leaves.
Repeat applications may be needed following label instructions.
Citrus leaf miner does not cause that much damage to mature trees but it can make them look bad. New trees may have their growth reduced and fruit production could be delayed. It you notice heavy leaf miner activity a spray may be needed at the next flush of new growth.