Thalaina clara Walker, 1855
Clara's Satin Moth
(previously known as Amelora amblopa)
DIPTYCHINI,   ENNOMINAE,   GEOMETRIDAE,   GEOMETROIDEA
 
Don Herbison-Evans,
(donherbisonevans@yahoo.com)
and
Stella Crossley


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

These Caterpillars are green, with a dozen or so narrow pale yellow wavy stripes along the body, and a conspicuous broader white and yellow line extending along each side. Another pair of distinct but broken yellow lines run ventrolaterally and extend down each leg. Each side of the head, the prothorax is extended into ear-like extensions, each with a reddish tip in late instars. The caterpillars have a thin 'waist' between each pair of segments, giving a wavy nature to the longitudinal lines. The wavy nature of these lines and the intersegmental rings distinguish these caterpillars from those of the similar species Thalaina selenaea. Otherwise the two species are very similar in feeding, the timing of the life stages, and even behaviour.


(Photo: courtesy of David Akers, Won Wron, Victoria)

The caterpillars lie characteristically along the central stem on the uppermost leaf of the foodplant. They quickly modifiy their posture in response to changes in lighting, turning to face a bright light. Perhaps this is to maximise light absorption or to blend in with illuminated surfaces. They are not true loopers, but do not use their first two pairs of prolegs which are reduced.


close-up of head
(Photo: courtesy of David Akers, Won Wron, Victoria)

The caterpillars have been found feeding on:

  • Black Wattle ( Acacia mearnsii, MIMOSACEAE ), and
  • Silver Wattle ( Acacia dealbata, MIMOSACEAE ).

    These plants have feathery (bipinnate) leaves, and the coloration and shape of the caterpillars gives them excellent camouflage on these plants. The caterpillars grow to a length of about 3 cms.


    pupa in part of its soil-covered cocoon
    (Photo: courtesy of David Akers, Won Wron, Victoria)

    The pupa is formed in a cell consisting of a loose cocoon in the soil or leaf debris. The pupa initially has a green body and brown abdomen, but later becomes entirely brown. In Melbourne pupation occurs in September.


    naked pupa
    (Photo: courtesy of David Akers, Won Wron, Victoria)

    The adults emerge about eight months later, at the beginning of May.


    The adult is a silky white, with a rusty 'N' shaped pattern outlined in black on each forewing. The forewing pattern is similar to that of Thalaina angulosa but that has a straight brown line from the base to near the middle of the margin, whereas Thalaina clara has a straight brown line from the costa to the tornus.


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

    The hindwings each bear a large brown dot at the wingtip, which is covered by the forewing when at rest.


    These markings also occur on the underside, but they are fainter, and the hindwing dot is divided into two halves. The half nearer the costa is orange, and the half by the hind margin is brown. The moth has a wingspan of about 5 cms.


    underside
    (Photo: courtesy of Dr David G. Hewitt, Melbourne, Victoria)

    The species is found in the southern half of Australia, including:

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


    Further reading :

    David Carter,
    Butterflies and Moths, Collins Eyewitness Handbooks, Sydney 1992, p. 203.

    Pat and Mike Coupar,
    Flying Colours, New South Wales University Press, Sydney 1992, p. 52.

    Marilyn Hewish,
    Moths of Victoria: Part 5,
    Satin Moths and Allies - GEOMETROIDEA (A)
    ,
    Entomological Society of Victoria, 2014, pp. 2, 5, 6-7, 30-31.

    Peter B. McQuillan,
    A review of the Australian moth genus Thalaina (Lepidoptera: Geometridae: Ennominae),
    Transactions of the Royal Society of South Australia,
    Volume 105, Issue 1 (1981) pp. 1-23.

    Francis Walker,
    Catalogue of Lepidoptera Heterocera,
    List of the Specimens of Lepidopterous Insects in the Collection of the British Museum,
    Part 3 (1855), p. 660, No. 2.

    Catherine J. 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 4 November 2011, 27 April 2023)