Leaf Miner

• Winding, pale serpentine tunnels or blotchy mines within the leaf — the larva visible as a dark speck inside
• Leaves may yellow and drop in heavy infestations
• Small, round puncture marks on leaf surfaces from adult feeding and egg-laying
• Most damage is cosmetic on established plants but can stunt seedlings

Leaf miners are the larvae of small flies. Adults lay eggs in punctures in leaf tissue; larvae hatch and feed entirely within the leaf. They pupate in the soil. Multiple overlapping generations occur through the growing season. Parasitic wasps commonly attack leaf miner larvae in the mines — they can provide significant natural control if not disrupted by pesticides.

1. 01Remove and dispose of mined leaves to reduce larval populations completing their cycle
2. 02Floating row cover prevents adult flies from reaching plants
3. 03Preserve natural parasitoid wasps — avoid applying broad-spectrum insecticides
4. 04Neem oil (azadirachtin) may deter egg-laying adults and affect larval development
5. 05Avoid over-fertilizing with nitrogen — rich, soft growth is more attractive to adults
6. 06On spinach and beet, harvest quickly rather than leaving plants to accumulate mines

If cosmetic damage is causing marketable loss in a larger planting, or you're seeing defoliation rather than isolated mines, an extension specialist can confirm the species and advise on parasitoid activity in your area.

• Leaf Miners— UC ANR Integrated Pest Management
• Leaf Miners on Vegetables— University of Minnesota Extension