Blackberry Leafminer: Appearance, Territory, Damage and Life Cycle

Latin Name: Metallus Rubi Appearance: Blackberries are more affected by leafminers than raspberries. They are also members of the sawfly family. Leafminers eat sensitive inner-leaf tissue. When leaves are held up to the light, the damage is most obvious. Blackberries are more affected by leafminers than raspberries. They are also members of the sawfly family. Leafminers eat sensitive inner-leaf tissue. When leaves are held up to the light, the damage is most obvious. Hosts Plants: Blackberry Territory: Europe and America Damage Insect Cause: Larvae mine between the top and lower leaf surfaces, feasting on delicate inner tissue and forming snake-like white tunnels. This may cause the leaves to dry up; extensive damage may cause the host plant to die or become seriously weakened as a result of a loss of chlorophyll and diminished photosynthesis. Life History and Habits: There is no visible egg; it is placed beneath the top epidermis, usually along a large vein. From there, a short, rapidly spreading corridor begins, with a lot of frasses, especially at the beginning. The passage widens into a massive, nearly full-depth splotch that frequently overruns the first corridor. Frass in loose grains, becoming bigger as the larva grows in size. The frass is dry, and it may collect like pepper grains in the lowest area of older mines. In the mine, a lone larva lies belly-up.