Birch leafminer (Fenusa pusilla) is the most common of several larval insects that mine birch leaves. This small sawfly is native to Europe but has become a major pest of birches in North America. The adult sawfly is a small, black, 4-winged insect. The larvae look like somewhat flattened, creamy white caterpillars when mature. Immature … Continue reading Birch Leafminer: A Toronto Master Gardeners Guide