Spodoptera mauritia (Boisduval, 1833)
Lawn Armyworm
(one synonym: Orthosia margarita Hawthorne, 1897)
AMPHIPYRINAE ,   NOCTUIDAE ,   NOCTUOIDEA
  
Don Herbison-Evans
(donherbisonevans@outlook.com)
and
Stella Crossley


These eggs were laid on the painted wall of a house, as a hairy irregular mass about 0.5 cms. across. The baby Caterpillars were white with big black heads, about 0.1 cm long. They descended from the wall on silken threads.


The young caterpillars are smooth-skinned and green with longitudinal lines.


Later, the caterpillars become brown with two rows of black triangles down the back. When disturbed, they drop, and curl into a spiral with the head in the middle.


They are an international agricultural pest on crops and pastures, feeding on plants from the family POACEAE such as:

  • Bermuda Grass ( Cynodon species ),
  • Kikuyu ( Pennisetum clandestinum ),
  • Sorghum ( Sorghum bicolor ), and
  • Rice ( Oryza sativa ),

    as well as:

  • Horsetail She Oak ( Casuarina equisetifolia, CASUARINACAE ).

    The caterpillars grow to a length of about 3 cms. They burrow into the soil below the plant where they pupate without a cocoon.


    (Photo: courtesy of Buck Richardson, Kuranda, Queensland)

    The adult moth is brown with a complex pattern of light marks on the forewings. The hindwings are plain pearly white. It has a wingspan of about 4 cms. The pheromones of this species have been identified.


    (Specimen: courtesy of the Macleay Museum, University of Sydney)

    The moth is preyed on by a Bolas Spider ( Celaenia species, ARANEIDAE ). This spider swings a silk thread with a sticky knob on the end, and emits a copy of the female moth's pheromone to attract the male moths.


    (Photo: courtesy of Boris Branwhite, Wyong Shire, New South Wales)

    Attempts to control the pest include the use of:

  • some sacking laid near the plants attacked, so that the caterpillars will hide under that by daytime, and they may be then collected and disposed of, or
  • a garden roller at midnight (when they come out to feed),
  • Hormones,
  • its Nucleopolyhedrovirus ( BACULOVIRIDAE ),
  • the nematode Steinernema carpocapsae ( STEINERNEMATIDAE ).

    The species occurs across Asia and the Pacific, including:

  • Borneo,
  • Hawaii,
  • India,
  • United Arab Emirates,

    as well as much of Australia, including :

  • Norfolk Island,
  • Western Australia,,
  • Northern Territory,
  • Queensland, and
  • New South Wales.

    In Sydney, counts were made of the number of adults coming to a nightly ultra-violet light, and the numbers totalled for each month of the year :

    JanFebMarAprMayJun JulAugSepOctNovDec
    9
    17
    23
    8
    16
    0
    4
    3
    42
    2
    0
    0


    Further reading :

    Jean-Baptiste Alphonse Dechauffour de Boisduval,
    Nouvelles Annales du Muséum d'Histoire Naturelle,
    Paris, Volume 2, Part 2 (1833), p. 240, No. 3.

    Ian F.B. Common,
    Moths of Australia,
    Melbourne University Press, 1990, fig. 49.1, pp. 61, 65, 462.


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    (updated 27 April 2013)