Currant aphid causes red, distorted areas on the leaves. Other aphids also infest currants. Spray with Sevin, malathion or rotenone. The insects can also be dislodged with high pressure water spray from the garden hose.
Four-lined plant bug causes round, brown, sunken spots on the leaves. The problem is not serious but is sometimes thought to be a disease. Use sprays of malathion.
Scales of several types may infest ribes. Use dormant oil in the spring before plants begin to grow. Crawlers are controlled with sprays of Sevin. The preferred method of control involves regular inspection for early detection then spraying with dormant oil.