Russian Wheat Aphid
Symptoms: White (in warm weather), or purple to red streaks (in cool weather) in leaves accompanied by inward rolling of the leaf. Rolling of the leaves protects the aphid by reducing the efficiency of predators and parasites as well as contact insecticides. Early detection is difficult because the pest tends to hide in the plant. Colonies are found most often in tightly rolled leaves near the base of the leaf, in leaf whorls, or concealed on the stem inside the flag leaf sheath.