Doratifera casta (Scott, 1864)
Black Slug Moth
(one synonym : Doratiophora acasta Froggatt, 1907)
Don Herbison-Evans
Stella Crossley & Ian Baird

Doratifera casta
(Photo: courtesy of Geoff Byrne, Kununurra, Western Australia)

These Caterpillars sting. When these caterpillars hatch, they feed communally. They sit on the leaf surface, touching each other, eating initially only the surface layer from the leaf.

Doratifera casta
(Photo: courtesy of Broderick Erwin, Victoria)

Later instars separate, and get a whole leaf each. The caterpillars have been found feeding on the foliage of various trees in MYRTACEAE, including:

  • Gum Trees ( Eucalyptus species ),
  • Bottlebrush (Callistemon species).
  • Water Gum ( Tristaniopsis laurina ),
  • Brush Box ( Lophostemon confertus ),

    as well as on

  • Wattles ( Acacia species, MIMOSACEAE ).

    Doratifera casta
    showing everted stinging hairs
    (Photo: courtesy of Geoff Byrne, Kununurra, Western Australia)

    The caterpillar is black, sometimes grey in the middle, with very pale green fleshy spikes along the back, and cream fleshy spikes along the sides of the caterpillar. Four of the spikes on the thorax protrude rosettes of cream stinging hairs if the caterpillar is disturbed. The contrasting coloration of the caterpillars offers a warning that these caterpillars sting. The head is brown, and normally tucked under the body. The caterpillars move like slugs because their legs are reduced.

    Caterpillar attacked by the bug Oechalia schellenbergii
    (Photo: courtesy of Jenny Holmes, Great Western, Victoria)

    The caterpillars are known sometimes to totally defoliate a tree, and are then considered to be a pest. However the caterpillars have many predators and parasites, which normally keep the population at tolerable levels.

    Doratifera casta
    caterpillars looking for a nice place to pupate
    (Photo: courtesy of Cheryl McCouat Photography, Rylstone, New South Wales)

    The caterpillars grow to length of about 2 cms. When fully grown, the caterpillars leave the foodplant and walk as far as 20 metres looking for a suitable crevice or piece of leaf litter in which to pupate.

    Doratifera casta Doratifera casta Doratifera casta
    Photos: courtesy of Geoff Byrne, Kununurra, Western Australia,
    and Don Herbison-Evans, Manly, New South Wales.

    The caterpillars pupate by rolling into ball with the underside outside, then encasing this in silk, and dousing this with a liquid that sets hard. Thus the pupa ends up being enclosed in a spherical brown woody cocoon, about 0.7 cm in diameter. The pupal period varies from 2 to 10 months.

    Doratifera casta
    (Photo: courtesy of Geoff Byrne, Kununurra, Western Australia)

    The adults have brown forewings, each with a diagonal row of four or more black dots, each outlined in orange. The hindwings are brown The moths have a wingspan of about 4 cms. The moths often sit with the forewings vertical, and the hindwings held horizontally, like skipper butterflies.

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

    The species occurs in:

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

    The adults may easily be confused with those of of Doratifera quadriguttata, but the adults of Doratifera casta are darker and the black spots are more distinct. This is one case where the caterpillars provide much clearer identification of the species.

    Doratifera casta
    egg mass
    (Photo: courtesy of Geoff Byrne, Kununurra, Western Australia)

    The eggs are white and spherical. They are laid in an irregular mass, and covered by the female moth in brown hair.

    Doratifera casta
    (Photo: courtesy of Geoff Byrne, Kununurra, Western Australia)

    Further reading :

    John L. Capinera (Ed.),
    Encyclopedia of Entomology,
    Springer Science & Business Media (2008), p. 1734.

    Ian F.B. Common,
    Moths of Australia,
    Melbourne University Press, 1990, figs. 29.1, 52.13, p. 302.

    James T. Costa,
    The Other Insect Societies,
    Harvard University Press (2006), pp. 577.

    Phillip W. Hadlington & Judith A. Johnston,
    An Introduction to Australian Insects,
    UNSW Press (1998), p. 64.

    Harriet, Helena, and Alexander W. Scott,
    Australian Lepidoptera and their Transformations,
    Australian Lepidoptera,
    Volume 1 (1864), pp. 18-19, and also Plate 6, top right.

    Australian Butterflies
    Australian Moths

    (updated 29 January 2013, 4 February 2023)