Leaf Miners

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Families: Lepidoptera, Hymenoptera, Coleoptera, Diptera

Description

Adult leaf miners include small moths (Lepidoptera), sawflies (Hymenoptera), beetles (Coleoptera), and flies (Diptera). Though there are many different leaf miner species, they all have small larvae about 3 mm long that tunnel into the leaves of plants creating mines and causing damage.

Life Cycle

Leaf miners overwinter as pupae in the leaf litter and garden debris. The adults emerge in early spring when the weather warms. After mating, the females lay eggs underside of leaves, especially new leaves. Some leaf miner species insert eggs into leaves. The larvae hatch from the eggs, chew into the layer between the leaf’s top and bottom, and start eating. Some leaf miners live their entire life cycle in one leaf. Others drop into the soil when finished growing and pupate. Several generations can occur for one year in most places and with most species. These can quickly multiply the number of larvae eating a crop.

Damage

The larvae of leaf miners excavate a mine into the tissue of leaves eating the leaf’s chlorophyll between the epidermal layers and leaving behind their waste material, called frass. Some leaf miners mine snake-like trails across the leaf, leaving long serpentine damage. Others remain in one place, creating a large leaf spot. In both cases, they affect the amount of chlorophyll in the leaf resulting in less photosynthesis to provide enough energy for the plant. Heavily infested leaves drop off the plant entirely which can affect plant growth. Edible plants such as spinach and ornamental plants such as azalea can lose marketability as they do not look nice.

Control

  • Nema Globe EFI Sticky Traps

Advice

  • Increase the vigor of plants through proper watering, fertilization, and aeration. Healthy plants can better withstand the leaf-miner damage and bounce back faster than stressed plants.
  • If there are a few leaves on plants with symptoms of leaf miner, cut and discard them.
  • Practice good garden sanitation by removing leaves and plant debris each season.

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