Spodoptera frugiperda (Smith, 1797)
Fall Armyworm
(formerly known as Phalaena frugiperda)
Don Herbison-Evans
Stella Crossley

Spodoptera frugiperda
(Photo: courtesy of James Castner, University of Florida)

These Caterpillars are brown with pale dorsal and dorso-lateral lines, and rows of dark spots along the back and sides. The undersides are pale brown. The head is dark brown with an inverted 'V' marking.

The natural diet of these caterpillars is

  • Grass ( POACEAE ),

    but they have become an international agricultural pest on crops and pastures, feeding on the flowers, fruit, and leaves of a wide variety of plants, including

  • Canola ( Brassica rapa, BRASSICACEAE ),
  • Peanuts ( Arachis hypogaea, FABACEAE ),
  • Cotton ( Gossypium species, MALVACEAE ),
  • Rice ( Oryza species, POACEAE ),
  • Sorghum ( Sorghum bicolor, POACEAE ),
  • Maize ( Zea mays, POACEAE ),
  • Apples ( Malus domestica, ROSACEAE ),
  • Oranges ( Citrus species, RUTACEAE ), and
  • Tobacco ( Nicotiana species, SOLANACEAE ).

    The attack of this species on crops can appear very suddenly, as the early instars require very little food, but later instars are voracious, totally destroying crops apparently ovenight.

    Curiously: the caterpillars have been reported not to attack a number of crops, although there is some confusion over the exact species that they dislike, but which may include:

  • Taro ( Colocasia esculenta, ARACEAE ),
  • Sweet Potato ( Ipomoea batatas, CONVOLVULACEAE ),
  • Yam ( Dioscorea species, DIOSCOREACEAE ), and
  • Cassava ( Manihot esculenta, EUPHORBIACEAE ).

    When food is short, the caterpillars become cannibals: attacking each other. The caterpillars grow to a length of about 4 cms. When mature: they burrow into the soil below the plant where they pupate without a cocoon.

    Spodoptera frugiperda
    (Photo: courtesy of Simon Ong, Kununurra, Western Australia)

    The adult moth is brown with a complex pattern of paler marks on the forewings. The males have bolder markings than the females. The hindwings are plain pearly white with narrow dark brown edges. The moth has a wingspan of about 3 cms.

    Spodoptera frugiperda
    (Photo: courtesy of CSIRO/BIO Photography Group, Centre for Biodiversity Genomics, University of Guelph)

    The pheromones of the species have been determined.

    Spodoptera frugiperda
    male (digitally repaired)
    (Photo: courtesy of CSIRO/BIO Photography Group, Centre for Biodiversity Genomics, University of Guelph)

    Attempts to control the pest include the use of:

  • intercropping with plants that they do not attack (as listed above),
  • intercropping with grasses that they prefer to attack,
  • intercropping with wild flowers to harbour predatory species such as beetles, mantids, and spiders,
  • using resistant varieties,
  • planting early using rapid growing and ripening varieties,
  • Bacillus thuringiensis Insecticidal Protein,
  • Parasitoids, and
  • Nematodes.

    Spodoptera frugiperda
    (Photo: courtesy of James Castner, University of Florida)

    The eggs are white, and laid in piles of about 100, and covered in hairs from the female's abdomen.

    The species originated in the Americas, in

  • Brazil,
  • Canada, and
  • United States of America,

    and now is found across the world in :

  • Ethiopia,
  • Ghana,
  • Korea,
  • South Africa,

    and has recently invaded Australia, being found, so far (July 2020), in

  • Queensland, Northern Territory, and Western Australia.

    Further reading :

    Sir James Edward Smith and John Abbott,
    The Natural History of the rarer lepidopterous insects of Georgia,
    T. Bensley (printers), London, Volume 2, pp. 191-192, and also Plate 96.

    Australian Butterflies
    Australian Moths

    (written 28 July 2020, updated 7 October 2020, 7 April 2022)