Sesamia calamistis (Pink Stalk Borer)

Life > Eukaryotes > Opisthokonta > Metazoa (animals) > Bilateria > Ecdysozoa > Panarthropoda > Tritocerebra > Phylum: Arthopoda > Mandibulata > Atelocerata > Panhexapoda > Hexapoda > Insecta (insects) > Dicondyla > Pterygota > Metapterygota > Neoptera > Eumetabola > Holometabola > Panorpida > Amphiesmenoptera > Lepidoptera (moths and butterflies) > Glossata > Coelolepida > Myoglossata > Neolepidoptera > Heteroneura > Ditrysia > Apoditrysia > Obtectomera > Macrolepidoptera > Noctuoidea > Family: Noctuidae

The Pink Stalk Borer is indigenous to Africa, occurring in savanna areas with a distinct dry season. Host plants include a wide variety of native grass species but also include cultivated grasses such as sugarcane, wheat and maize.

Life cycle

The life cycle is usually completed in 6-8 weeks during the summer months, but takes longer if part of it takes place in the winter months. There are no distinct generations: eggs, larvae, pupae and adults can all be present in a population at any one time.

Adults. The adults emerge from their pupae and mate in the usual moth fashion where the female releases a sex pheromone that attracts a male from downwind.

Eggs. The female moth, once mated, lays her eggs at night under the leaf sheaths of plants, in batches of up to 100 or more. Eggs hatch about a week after being laid.

Larvae. Soon after emergence, the larvae bite into the stem of the grass or, on maize, through the sheathing leaves into the maize cobs. Caterpillars move on to new plants once the one they have been feeding on has died from their feeding activities. Larval development takes 3-6 weeks in summer during which time they normally pass through 6-7 instars.

Pupae. Final instar larvae spin a cocoon round themselves, inside the hollowed-out stem of the plant or in the sheathing leaves or, in the case of maize, in the tunnels they have made in the cob. Inside the cocoon they moult into pupae and after 2-3 weeks the adult emerges.

Find out more about pests of maize in southern Africa


  • Annecke, D.P. & Moran, V.C. 1982. Insects and mites of cultivated plants in South Africa. Butterworths, Durban.

  • Chinwada, P. & Overholt, W.A. 2001. Natural enemies of maize stemborers on the highveld of Zimbabwe. African Entomology 9: 67-75.

Text by Hamish Robertson

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