Stemborers

Stemborers are of greatest importance as pests of maize in Africa, but they also attack other cereal crops such as sorghum, millet and sugarcane. Damage is caused by larvae which first feed on young leaves, but soon enter into the stems. During early stage of the crop growth larvae may kill the growing points resulting in dead hearts.

Stemborer larva inside a maize stem

In Eastern Africa there are two species of stemborers which cause heavy damage to cereal crops –Busseola fusca and Chilo partellus. Busseola fusca is indigenous to Africa and is present in high and mid altitude areas (3500 ft and above sea level). Chilo partellus accidentally came to Africa from Asia in 1930s. Chilo partellus is present on low and mid altitude areas (zero to 4000 ft above sea level). Adult moths lay eggs on maize plants, larvae emerge and after feeding on leaves for two to three days enter inside maize stems. Busseola fusca lays its eggs between stem and leaf sheaths, whereas Chilo partellus lays its eggs on plant surface in form of egg batches. Life cycle of Busseola fusca

Life cycle of Busseola fusca

After larvae bore into maize stems, they feed and grow within maize stems for 2-3 weeks. When larvae are fully grown, they pupate and remain inside maize stem. After 7-14 days adults emerge from pupae and come out of the stem. They mate and lay eggs on maize plants again and continue damaging the crop.