While European, white, gray and paper birches are most susceptible, yellow and river birches are also affected. Not only do these insects destroy your tree's ornamental beauty, but repeated birch leaf miner attacks weaken your birch trees' resistance to bronze birch borers. Larvae do not develop in mature leaves. Small, flattened, white larvae appear seven to ten days later. For 10 to 12 days they mine leaves, consuming tissue between the upper and lower leaf surfaces.
Leaves turn brown and paper-like and finally drop off.
After 10 to 15 days, the mature larvae cut a hole in the leaf, fall to the ground and pupate. During the summer they spend 15 to 20 days in the soil and re-emerge as adults. They repeat this cycle producing three to four generations from May to August. The first or spring infestation of birch leaf miner is the most serious. All of the leaves can be affected, making the tree look blighted.