Leafminers are the larvae of flies, moths, beetles, or sawflies. The larvae feed between the upper and lower surfaces of the leaves. The adult female moths lay their eggs on or inside the leaves, usually in early to late spring. The emerging larvae feed between the leaf surfaces, producing blisters, blotches, or trails. The infested tissue stands out prominently against the normal green foliage as it turns whitish or light green to brown. The insects pupate inside the leaves or in the soil and emerge as adults. Some adults also feed on the leaves, chewing holes or notches in them. For more information about leafminers, see Leafminers.
Control of leafminers is difficult because they spend most of their lives protected inside the leaves. Insecticides are usually aimed at the adults. Once leafminers are noticed in the leaves, inspect the foliage periodically; or check with your local County Extension Agent (see County Extension Agents) to determine when the adults emerge. Then spray with an insecticide containing acephate, carbaryl, or diazinon. Make sure your plant is listed on the product label.
