leaf miner

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of numerous insects, especially moths and flies, that in the larval stage burrow into and feed on the internal tissue of leaves.

from The Century Dictionary.

• noun S. graminum, a congeneric European insect, also occurring in the United States. It is also called imported cabbage leaf-miner.
• noun The larva of a moth of the family Tineidæ: so called because these caterpillars feed mostly on the parenchyma of leaves, and between the upper and lower surfaces.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An insect larva that lives within leaf tissue.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun any of various small moths or dipterous flies whose larvae burrow into and feed on leaf tissue especially of the family Gracilariidae
• noun any of various small moths or dipterous flies whose larvae burrow into and feed on leaf tissue especially of the family Gracilariidae