Beet armyworm

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E. Nissen-Petersen, Kenya
Is this a Minor Pest?
Minor Pest Title

Beet armyworm (Spodoptera exigua)

Minor Pest Description

Armyworms may damage sweet potatoes. Young caterpillars scrape sweet potato leaves, while the older caterpillars feed producing large irregular holes and may leave only the veins. Mature caterpillars measure up to 4 cm long and are generally black, heads faintly mottled with dark brown spots and with light yellow stripes at their backs (IRRI, 2001).


Predatory bugs, carabid beetles, spiders and wasps attack the caterpillars, and many parasitic wasps are also known to attack armyworms. Fungal diseases have been observed infecting caterpillars in the field.

Minor Pest What to do.
  • Eliminate weeds
  • Collect and destroy leaves containing eggs and caterpillars
  • Light traps can be hung over basins of water in the field to trap the adults at night
  • When necessary the biopesticide Bt can be used for control of this pest. For more information on Bt click here
Minor Pest Position
Minor Pest Firstcontent
Pest Type
Host Plants
Sweet potato