Stibaroma melanotoxa Guest, 1887
Grey-caped Line-moth
NACOPHORINI ,   ENNOMINAE ,   GEOMETRIDAE ,   GEOMETROIDEA
 
Don Herbison-Evans
(donherbisonevans@outlook.com)
and
Cathy Young & Stella Crossley

Stibaroma melanotoxa
early instar, magnified
(Photo: courtesy of Cathy Young)

These Caterpillars are nocturnal feeders, accepting the leaves of:

  • various species of Gum Trees ( Eucalyptus, MYRTACEAE ).

    Stibaroma melanotoxa
    (Photo: courtesy of Cathy Young)

    The body surface has a rough appearance. Individual caterpillars vary in colour from orange to red-brown. Abdominal segments two, three, and eight have small paired dorsal horns. The first pair of ventral prolegs is absent and the second and third pairs are reduced in size, and do not appear to clasp the stem. The anal prolegs are extended sideways, giving the anal segment a forked appearance. Some forms are plain brown, and some have a set of four narrow black bands around the body.

    Stibaroma melanotoxa
    (Photo: courtesy of Merlin Crossley, Melbourne, Victoria)

    During the day, the caterpillars either stretch out and press against a stem, or they loop the front of the body into a circle so that the head and thorax lie on top of the abdomen. In this position, the caterpillar looks as if it has tied itself into a knot. We have seen this unusual posture in only one other species, (curiously: in a totally different family) namely Ischyja ebusa. The caterpillar grows to a length of about 4 cms.

    Stibaroma melanotoxa
    (Photo: courtesy of Merlin Crossley, Melbourne, Victoria)

    In Melbourne, pupation took place in early August, and the adlut moths emerged some seven months later in February the following year.

    Stibaroma melanotoxa
    (Photo: courtesy of Merlin Crossley, Melbourne, Victoria)

    The adult moth has grey forewings with black transverse stripes and veins.

    Stibaroma melanotoxa
    (Photo: courtesy of Cathy Young)

    The hindwings and the undersurfaces of all four wings are silver with a broad black band along the margin. The wingspan is about 3.5 cms.

    Stibaroma melanotoxa
    male
    (Photo: courtesy of Marilyn Hewish, Moths of Victoria: Part 5)

    The species occurs in:

  • New South Wales,
  • Australian Capital Territory,
  • Victoria,
  • Tasmania, and
  • South Australia.

    Stibaroma melanotoxa
    (Photo: courtesy of Merlin Crossley, Melbourne, Victoria)

    Females captured in in April in Melbourne deposited neat rows of eggs along the edges of leaves. The eggs hatched after about 18 days.

    Stibaroma melanotoxa
    eggs mmagnified
    (Photo: courtesy of Cathy Young)


    Further reading :

    Edward Guest,
    A classified list of Geometrina found around Balhannah, with notes on species,
    Transactions of the Royal Society of South Australia,
    Volume 9 (1887), p. 140, No. 22.

    Marilyn Hewish,
    Moths of Victoria: Part 5
    Satin Moths and Allies - GEOMETROIDEA (A)
    ,
    Entomological Society of Victoria, 2014, pp. 16-17.

    Cathy Young,
    Characterisation of the Australian Nacophorini and a Phylogeny for the Geometridae from Molecular and Morphological Data,
    Ph.D. thesis, University of Tasmania, 2003.


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    (updated 27 May 2010, 28 November 2014)