Large, irregular holes appear in leaves. Black frass (droppings) also usually visible.
Cultural measures: Remove and destroy clusters of eggs when seen. Pick off by hand where possible. Product Solution: Spray with Sprayday Greenfly Killer or Provado Ultimate Fruit and Vegetable Bug Killer Ready to Use/Concentrate, Organic Bug free or for smaller specimens Provado Ultimate Bug Killer Ready to Use/Concnentrate.