At least three stem borers are known to damage maize, of which the Chilo borer (Chilo partellus) and the maize stem borer (Busseola fusca) are the most common. Young caterpillars feed in whorls but older caterpillars bore into stems and ears. The Chilo borer moth is elongated, light brown in colour, while the maize stem borer is a stout brownish moth. Eggs of the maize stem borer are laid in egg batches (not covered) behind the leaf sheath (between leaf and stem), and the Chilo borer lays egg batches on both the upper and lower surface of leaves. The pupae are formed inside the tunnels, within ears or stems.