Cereal Leaf Beetle
Cereal leaf beetle (Oulema melanopus) colonizes wheat, oats, and other small grains. Beetles infest wheat and other grains in the early spring and often build-up very high populations. The larvae pupate and resulting adults emerge in late-May/early-June from these fields. The adults emerge as the grain crops are maturing and migrate to corn fields to find food. If corn is adjacent to infested small grain plants may become highly infested with the beetles, especially along edges nearest the small grains. Cereal leaf beetles eat the leaf surface tissue on whorl stage plants. See scouting guidelines for whorl feeding insects. Feeding scars appear as long and narrow streaks eaten between leaf veins, usually on the upper surface. Even when beetle populations are very high, leaf feeding is usually cosmetic. However, injury is often alarming to farmers even if it poses no economic threat. Beetles do not reproduce or remain for a very long time in corn fields and, therefore, injury is a single, short term event that fast growing corn plants soon overcome.