Sawfly larvae are the cause of severe leaf damage to a wide range of plants. They feed in groups and are usually found around the edges of leaves. They look like Caterpillars but are not related to butterflies or moths. Picking off when spotted is the only real organic control method for this pest. They are leaf feeders and there are many different secies including; Apple Sawfly, Plum Sawfly, Gooseberry Sawfly and Solomons Seal Sawfly.