The Mediterranean corn stalkborer (Sesamia nonagrioides), is an serious pest of maize in Southern Europe and North Africa. It can also attack sorghum, sugarcane, wheat, rice and barley.
Life cycle and appearance of Mediterranean corn stalkborer
The adults have a wingspan of 30-40 mm and greyish yellowish forewings marked with a marginal band and indistinct black dots. The hindwings are white.
The eggs are grooved, whitish when laid and turning pinkish later. The larvae are 30-40 mm long when fully developed and yellowish to brownish with a rust-coloured back. The pupae is about 20 mm long and chestnut brown.
In Mediterranean regions, four generations occur per year and adult flights begin in March; other, sometimes more significant flights occur in April, June, August and October. The eggs are laid on the underside of leaves in small clusters of about ten and hatch after about a week. The larvae feed on the leaves for a few days and then bore into the stems where they continue to feed. Development takes 40-50 days. Pupation usually takes place in the feeding galleries. Fully grown larvae overwinter in the host plants.
Larvae feed in stems, eating out frass-filled galleries. Stem tunnelling may kill growing points, resulting in 'deadheart' symptoms as terminal leaves die, and may also cause stem breakages. Larvae may also feed in maize cobs and in inflorescence stalks of other cereals.