Ypthima arctous (Fabricius, 1775)
Dusky Knight
(one synonym : Yphthima arctoides Hewitson, 1865)
Don Herbison-Evans
Stella Crossley

Ypthima arctous
(Photo: courtesy of Nick Monaghan, Tewantin, Queensland)

The Caterpillar of this species feeds on various grasses (POACEAE), and happily accepts :

  • Cogon Grass ( Imperata cylindrica ),
  • Blue Couch ( Digitaria didactyla ), and
  • Kangaroo Grass ( Themeda triandra ).

    The caterpillars are hairy. Initially the caterpillars are buff coloured. Later instars are green, and the last instar has darker lines along the body. The caterpillar has a pair of horns on the tail. It grows to a length of about 2 cms.

    The pupa is suspended head down from a cremaster. It can be any colour from green to brown, and has brown markings.

    Ypthima arctous
    (Photo: courtesy of Martin Purvis, Ingleburn, New South Wales)

    The adult is dark brown with an eyespot on each wing. The eyespots on the forewings have two blue spots in them. The undersides are similar to the upper surfaces but a little paler. The wingspan is about 3 cms.

    Ypthima arctous
    egg, magnified
    (Photo: courtesy of Ken Walker, Nowa Nowa, Victoria)

    The eggs are pale green or yellow, with a diameter of about 1mm. Each is approximately spherical, with about 1,000 shallow hexagonal dimples.

    The species occurs in

  • New Guinea, and
  • Sulawesi,

    and also in Australia in

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

    Ypthima arctous
    mating couple
    sorry about the dark line shadow of the grass stem
    (Photo: courtesy of Nick Monaghan, Tewantin, Queensland)

    Further reading :

    Michael F. Braby,
    Butterflies of Australia,
    CSIRO Publishing, Melbourne 2000, vol. 2, pp. 478-479.

    Johan Christian Fabricius,
    Historiae Natvralis Favtoribvs,
    Systema Entomologiae (1775), p. 489, No. 202.

    Wesley Jenkinson,
    Life history notes on the Dusky Knight, Ypthima arctous (Fabricius, 1775) Lepidoptera: Nymphalidae,
    Metamorphosis Australia,
    Issue 67 (December 2012), pp. 14-16,
    Butterflies and Other Invertebrates Club.

    Ross Kendall,
    A new location for the Dusky Knight, Ypthima arctous (Fabricius, 1775) (Lepidoptera: Nymphalidae: Styrinae),
    Butterflies and Other Invertebrates Club,
    Metamorphosis Australia,
    Issue 63 (December 2011), p. 33.

    Buck Richardson,
    Tropical Queensland Wildlife from Dusk to Dawn Science and Art,
    LeapFrogOz, Kuranda, 2015, p. 231.

    Australian Butterflies
    Australian Moths

    (updated 7 May 2008, 13 December 2013, 17 March 2015, 30 June 2020, 24 September 2021)