Leaf-Miners
Many plants are liable to have their leaves mined by the larvae of minute insects, which may belong to various groups--Beetles (Orchestes Fagi in Beech-leaves, &c.), Sawflies (species of Fenusa, &c.), Lepidoptera (species of Lithocolletis, &c.), and Diptera (species of Phytomyza, &c.). In general, the affected plants seem to suffer little harm from the existence of the mines, unless these are very numerous. This is fortunate, as the only remedy is to crush the larvae in the leaf between the finger and thumb--a remedy not suitable for extensive application. See also Celery Fly, Holly-leaf Fly, and Parsnip Fly.