How to Rid Plants of Leaf Miners

Leaf miner feeding acitivity leaves white to silver tissue lines in the foliage or needles of a plant.

Leaf miners are equal opportunity pests that can be found on edible, ornamental and needled plants. They are the larva of flies, moths or beetles and feed on the tissue just under the leaf surface. They cause characteristic patterned damage in the foliage as they feed. There are leaf miners that are specific to individual plants such as elm and aspen leaf miners. The variety of leaf mining insects makes control difficult but since the feeding activity doesn't hurt the plant it is often not necessary. Leaf miner controls are most effective if applied when eggs are in evidence.

Things You'll Need

• Garden shears
• Hose
• Hose end insecticide sprayer
• Measuring cup
• Contact insecticide (Pyrethroid)
• Systemic neonicotinoid insecticide

Instructions

1. Prune or cut out any infected plant tissue and destroy it. Topical chemical controls are often ineffective because the leaf miner is under the surface of the leaf and protected from contact with poisons. Physical removal of the insect is safe and nontoxic.

2. Spray when the eggs are just visible on the under side of the leaves. A pyrthroid based insecticide has shown some control when applied before hatching. It will not affect the already hatched and burrowing larvae which is why the timing is important. Apply it in early spring by loading a hose end sprayer with the amounts recommended by the manufacturer.

3. Saturate the upper and lower parts of the leaves as well as the woody parts of the plant. Pyrethrins are classified as botanical control measures and are safe to use near edible crops.

4. Bring out the big guns if the leaves are already showing signs of damage. The only remedy is a chemical control that can be sprayed on through a hose end sprayer. A systemic insecticide will get into the plant tissue and the larvae will ingest the poison when it feeds.

5. Apply neonicotinoids to soil or to foliage. Mix the product in the amount recommended by the manufacturer in the hose end sprayer. Either apply as a soil drench or foliar treatment. When applied to soil it will provide control that is absorbed by roots.

6. Control leaf miners that are found on edible leaves such as spinach manually. Remove the leaves that already have tracks and look daily for signs of eggs under the leaves. Destroy any infested material so the larvae don't develop.

References

• "Colorado State University Extension"; Leafmining Insects; W.S. Cranshaw, J.R. Feucht; January, 2009
• "University of Florida IFAS Extension"; Leafminers on Ornamental Plants; Eileen A. Buss