Sycamore Leafblotch Miner (Ectoedemia platanella Clemens)

From Bugwoodwiki

Leininger, T.D; Solomon, J.D.; Wilson, A. Dan; Schiff, N.M. 1999. A Guide to Major Insects, Diseases, Air Pollution Injury, and Chemical Injury of Sycamore. Gen. Tech. Rep. SRS-28. Asheville, NC: USDA Forest Service, Southern Research Station. 44 p.

Leafblotch miner larvae are pale green, slightly flattened with a retracted head, up to 4 mm long, living singly within distinct leaf mines. The tiny adult moth is seldom seen, but it ranges over much of the Eastern United States. Ectoedemia leaf injury appears as a brown, circular blotch mine (+ 1 cm diameter) just below the leaf cuticle. Mines originate from a narrow entrance mine and are filled with frass in the center (fig. 8). Heavily mined leaves drop prematurely. Injury is unsightly, but its impact on tree health usually is slight to negligible. Natural enemies control most populations. Direct controls are rarely needed.