THE AFRICAN ARMYWORM
Spodoptera exempta Walker (Lepidoptera: Noctuidae)
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Photo: (c) ARC |
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Click HERE to read about the 2003 armyworm outbreak in SOUTH AFRICA
Information about the African Armyworm has been extracted from:
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"The African Armyworm Handbook: The status, biology, ecology, epidemiology and management ofSpodoptera exempta (Lepidotera: Noctuidae)." Second Edition. Chatham Maritime, Kent ME4 4TB, United Kingdom.
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"Crop Pests in southern Africa. Vol.4 1989. Field crops and pastures. Bulletin 416. A.C. Myburgh (ed.). Plant Protection Research Institute, "
Scientific nomenclature
Class : Insecta
Order : Lepidoptera
Family : Noctuidae
Genus : Spodoptera
Species : exempta (Walker)
Common names :
English (Africa): African armyworm; mystery worm; hail worm; rain worm
Malawi : nchembere, zandonda (= old ladies follow each other), chipakusu, kapuchi
Mozambique : nyanja
South Africa : kommandowurm
Tanzania : viwavi jeshi, ng'urrto
Zimbabwe : nhundururu, imhogoyi
The African armyworm is an important economic pest of pastures and cereal crops (maize, wheat, sorghum, millet, teff and rice), and occurs widespread in East, Central and Southern Africa and parts of Arabia and Australasia.
Normally only small numbers of this pest occur- usually on pastures, but periodically the populations increase dramatically and mass migration of moths occur, covering many thousands of square kilometres and traversing international boundaries.
Outbreaks follow the onset of wet seasons when dry grasslands produce new growth and cereal crops are planted. Major outbreaks of armyworm are commonly preceded by extended drought.
Life Cycle:
Egg: Individual eggs are conical with a slightly rounded apex, and about 0.5mm in diameter. They are pale yellow in colour when newly laid, but darken until just before hatching. Head capsules of the larvae are visible through the eggshells.
The African armyworm adapts well to its' environment by undergoing physiological and genetic changes. Larvae occur in two colour forms. These are the black, crowded or gregarious form with a black head, and the green, non-crowded or solitary form with a pale speckled head. The crowding of larvae results in changes in both their colour and behaviour, creating what appears to the 'untrained eye', to be two different species!
