What are they and how to control them
The citrus leafminer is an insect pest that started showing up in Southern California several years ago. The larvae are laid by tiny, minute, silvery white moths that tunnel within the leaves, leaving snaking trails of dead tissue behind. Other symptoms of infestation include curling of leaves and, in severe cases, even succulent young branches of green shoots may be attacked.
Although leaf miners don’t usually demolish an entire plant, they can cause quite a bit of unsightly damage. This makes it important to start controlling this pest at the first signs of attack and following up with repeat applications to break the life cycle of this insect pest. Leafminer Traps can be set out to detect these pests and are sold in specialty lawn and garden stores such as Grangetto’s.
Citrus leafminers tunnel between the upper and lower surfaces of leaves to lay eggs. The clear waxy trail they leave behind is unmistakable–and permanent. Once they eat a path between leaf surfaces, they drop off the leaf to pupate in the soil beneath. Then the whole process starts over again, yielding several generations of leaf miners over the course of a summer.
Controlling leafminers is difficult, even with chemicals, because they are protected by the upper and lower leaf surfaces. We recommend treating your infected plants with an insecticide containing Spinosad, such as Monterey Garden Insect Spray with Spinosad . Another effective control is to remove (and destroy) affected leaves. You can also treat the leaf surface with a oil-based pesticide, such as Neem Concentrate, which can help to prevent tunneling by future generations.
More about Citrus Leafminer
Images courtesy of UC IPM Online