General Information

Common name: Corn borer
Scientific names: Ostrinia furnicalis, O. nubilalis
Lepidoptera: Crambidae

Synonyms: Asian corn borer, Oriental corn borer, European corn borer

Host plants

Corn is the preferred crop but it will infest other plants, including bean, cotton, tobacco, beet, celery, potato, pepper, tomato, soybean, sorghum, and weeds.

Distribution

Asia and in all areas where corn is grown

Damage

Corn borer larvae begin feeding on leaf surface or in the whorl. There are pinholes on leaves at the whorl stage. As the plant grows, they bore holes into leaf midribs down into the stalks. Excreta or frass are found near entrance holes. Tassels are clumped where they later feed. Stalks and tassels are broken. They feed last on corncob and cause ear to drop, in severe cases (PCARRD, 1981).

Description

The egg is white and laid in masses like fish scales. An egg mass has 5-50 eggs. The egg mass or 2-3 more can be found on the plant leaf. Eggs become cream-colored and dull as they mature. Before hatching, the black heads of the larvae can be seen through the transparent egg membrane. Eggs hatch 4-9 days later.

The larva is flesh colored, ranging from light gray to light pink with small round dark brown spots on each segment. The larva has a brown head and indistinct reddish stripes running the length of its body. A mature larva is about 2-3 cm in size. The reddish brown pupa is found inside the larval home (inside the stems or ear where it has been feeding).

The pupa is reddish-brown and approximately 2-2.5 cm long with segments evident on half of the body. The pupal stage lasts about 2 weeks.

The adult female is a creamy, brownish yellow moth, and about 3 cm long. The forewings of the female are usually lighter in color than that of the male. The hind wings of both males and females have light markings. The reddish-brown male has a long slender body and is smaller than the female (Bureau of Plant Industry, 1987: pp. 13-14).