Achaea janata (Linnaeus, 1758)
Castor Oil Looper or Croton Caterpillar
(one synonym : Ophiusa ekeikei Bethune-Baker, 1906)
Don Herbison-Evans
Stella Crossley

Achaea janata
(Specimen: courtesy of Peter Rehbein, Innes Park, Bundaberg)

The caterpillars are initially brown with a black and white head, a red knob on the tail, and a black mark on the back of the second abdominal segment. The spiracles on each side of the abdominal segments are black. In the last instars, the brown turns to bluish-grey, and the point on tail turns black. The underside and legs become orange.

Achaea janata
(Photo: courtesy of Don Gardner, Murphy's Creek, Queensland)

The first pair of prolegs of the caterpillars is degenerate, and so the caterpillars move in a looper fashion.

The caterpillars are a pest on:

  • Noni ( Morinda citrifolia, RUBIACEAE ), and
  • Rambutan ( Nephelium lappaceum, SAPINDACEAE )

    and a pest at times on

  • Castor Oil Plants ( Ricinus communis, EUPHORBICEAE ),
  • Tamarind ( Tamarindus indica, CAESALPINIACEAE ), and
  • Hoop Pine seedlings ( Araucaria cunninghamii, ARAUCARIACEAE ).

    Specimens have also been found feeding on many other plants, including :

  • Croton ( Codiaeum variegatum, EUPHORBICEAE ),
  • Grey Mangrove ( Avicennia marina, ACANTHACEAE ),
  • Orchid Trees ( Bauhinia species, CAESALPINIACEAE ),
  • Green Rose ( Aeonium canariense, CRASSULACEAE ),
  • Soybeans ( Glycine max, FABACEAE ),
  • Cotton ( Gossypium hirsutum, MALVACEAE ),
  • Wattles ( Acacia species, MIMOSACEAE ),
  • Gum Trees ( Eucalyptus species, MYRTACEAE ),
  • Three Corner Jack ( Emex australis, POLYGONACEAE ),
  • Macadamia Nuts ( Macadamia integrifolia, PROTEACEAE ),
  • Roses ( Rosa odorata, ROSACEAE ),
  • Lychee ( Litchi chinensis, SAPINDACEAE ),
  • Puncture Vine ( Tribulus species, ZYGOPHYLLACEAE ),

    Achaea janata
    pupa in cocoon
    (Photo: courtesy of Geoff Byrne, Broome, Western Australia)

    The caterpillars grow to a length of about 5 cms. They pupate in a sparse white silk cocoon between leaves and stems of the foodplant. The pupa is brown but covered in a fine white powder.

    Achaea janata
    (Photo: courtesy of John Lahey, Fort Bushland Reserve, Queensland)

    The adult moth has forewings that have a pattern of light and dark brown. The hindwings are black with three white spots along the margin, and an unbroken white band across the middle. The moth has a wingspan of about 6 cms.

    The adult moth is known to feed on fruit juice, and is suspected of piercing fruit to obtain it. A number of control measures have been proposed.

    Achaea janata
    (Specimen: courtesy of Dawn Bishop, Bundaberg, and
    the Macleay Museum, University of Sydney)

    The eggs are laid under a foodplant leaf in an irregular cluster. The eggs are spherical and minutely ribbed. Initially they are pale green, and develop red markings as hatching approaches.

    Achaea janata
    eggs, magnified
    (Photo: courtesy of Geoff Byrne, Broome, Western Australia)

    The pheromones of the species have been studied.

    Achaea janata
    Cocos Islands 1982

    The species occurs in :

  • Borneo,
  • Cook Islands,
  • Hawaii,
  • Japan,
  • New Guinea,
  • New Zealand,
  • Seychelles,
  • Taiwan,

    as well as most of Australia including:

  • Western Australia,
  • Northern Territory,
  • Queensland,
  • New South Wales,
  • Victoria,
  • Tasmania, and
  • South Australia.

    Achaea janata
    (Photo: courtesy of Graeme Cocks, Townsville, Queensland)

    Further reading :

    David Carter,
    Butterflies and Moths,
    Collins Eyewitness Handbooks, Sydney 1992, fig. 46.10, p. 259.

    Ian F.B. Common,
    Moths of Australia,
    Melbourne University Press, 1990, fig. 46.10, p. 453.

    Wesley Jenkinson,
    Moths photographed at Obum Obum,
    Metamorphosis Australia,
    Issue 73 (June 2014), p. 31,
    Butterflies and Other Invertebrates Club.

    Carl Linnaeus,
    Insecta Lepidoptera,
    Systema Naturae,
    Volume 1, Edition 10 (1760), Class 5, Part 3, p. 527, No. 184.

    Peter Marriott,
    Moths of Victoria - Part 8,
    Night Moths and Allies - NOCTUOIDEA(B)
    Entomological Society of Victoria, 2017, pp. 11, 22-23.

    Buck Richardson,
    Tropical Queensland Wildlife from Dusk to Dawn Science and Art,
    LeapFrogOz, Kuranda, 2015, p. 124.

    Paul Zborowski and Ted Edwards,
    A Guide to Australian Moths,
    CSIRO Publishing, 2007, p. 195.

    Australian Butterflies
    Australian Moths

    (updated 30 May 2013, 18 March 2017, 8 November 2020, 11 April 2022)