Answer: You are describing leaf minors. They are the larvae of a flying insect. Adult females deposit eggs within leaf tissue. Larvae hatch from eggs in a few days and begin to feed on internal leaf tissues. Mature larvae emerge from inside the leaf and drop to the soil where they pupate in soil crevices, or in rare cases, they may pupate on the leaf. The timespan from egg to adult is less and three weeks under optimum conditions, so many generations occur annually. Because the larvae are within the tissues of the leaves, there are no chemical controls. You can pick off the affected leaves to prevent the larvae from exiting and turning into an adult. You can also keep fallen leaves picked up and you can work the soil beneath your plants to either bury or expose the little pests. Eventually you will rid your plants of leafminers.
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