Leaf miners are a common garden pest that affects beet, chard, and spinach leaves. Leaf miners are actually maggots that tunnel through the tissues of leaves, creating large burnt dry-looking spots on the leaves, seen below. Leaf miner damage is most commonly seen in the spring.
How do I get rid of Leaf Miners?
- The best solution is to remove affected leaves from the plants. Cut the bad leaves from the plant and throw them away. Do not put them in your compost pile. Wash your hands after pruning to avoid spreading their eggs to other plants.
- Regularly check beet, chard, and spinach leaves for small white eggs. If you see the eggs, crush them gently with your hand.
- Leaf miners have a number of natural enemies. Therefore sometimes you can wait and nature will take care of the problem for you.
- If you continue having the problem, try applying the organic insecticide Spinosad. Spinosad needs to be ingested by the leaf miner to be effective, so spray the leaves weekly throughout the season.
- When planning your garden, try planting companion plants to help prevent leaf miner damage on vegetables. Several “trap crops” taste delicious to leaf miners, and will attract them away from your edible vegetables. Lambsquarter, columbine, and velvetleaf are good trap crops – but may somewhat be casualties of war!
What Are Leaf Miners?
- Leaf miners are maggots that live in between the plant tissue. Their larvae come from small gray flies. They feed off of the leaf tissue, eating layers with the least amount of cellulose. The feeding causes tunneling injuries to the leaf, which dry out over time. This is when you know your plants are infected.
- There are three types of leaf miners found on vegetables. The type found in gardens is almost always the Spinach Leaf Miner. Adult flies emerge in the spring to lay eggs on the underside of leaves. Problems are most common in gardens where spinach and beets are overwintered and continuously grown, providing host plants for the insects during the winter.