Chlenias auctaria Guenée, 1857
NACOPHORINI ,   ENNOMINAE ,   GEOMETRIDAE ,   GEOMETROIDEA
 
Don Herbison-Evans
(donherbisonevans@outlook.com)
and
Dave Britton & Stella Crossley

Chlenias auctaria
(Photo: copyright Dave Britton)

This Caterpillar is black with a pattern of fine parallel pale yellow lines, a thin orange dorsal stripe, and a yellow band along each side. Its head capsule and anal segment are blue-green speckled with black. Its legs are red.

Chlenias auctaria
(Photo: courtesy of Abby Phillips, Caulfield South, Victoria)

This species has been recorded as feeding on over 17 species of unrelated plants, including:

  • Gum Trees ( Eucalyptus, MYRTACEAE ),
  • Wattles ( Acacia, MIMOSACEAE ),
  • Needlewood ( Hakea, PROTEACEAE ),
  • Boneseed ( Chrysanthemoides monilifera, ASTERACEAE ),

    and has also adapted to feeding on the introduced

  • Monterey Pine ( Pinus radiata, PINACEAE )

    to the point where it is a pest in pine plantations.

    Chlenias auctaria
    close-up of head and thorax
    (Photo: courtesy of Abby Phillips, Caulfield South, Victoria)

    The species has been studied to discover how and why it is so polyphagus. It was found that the mean pupal size of was significantly reduced by feeding on Pinus radiata (a non-native plant host) compared to two native host plants (Eucalyptus obliqua and Acacia mearnsii). The main reason for this seemed to be the higher ratio of dry weight to wet weight of plant material in the native plants compared to the introduced plant species; the larvae on Pinus radiata simply could not get enough nutrient to catch up to those feeding on the native plant species. So given that it develops poorly on such plants, why does it continue to use them for food?

    It appears that the polyphagous nature of this species may be related to the dispersal behaviour in this group. First instar larvae are active dispersers, and spend the first two days of their life moving about by climbing to the top of the plant upon which the eggs were laid, spinning a silk balloon, then ballooning to other plants. The choice made by adult female moths appears to have little effect on the host that the larvae end up eating. Larvae must feed within two days of dispersal; whatever plant they end up on at the end of two days dispersal becomes their food plant, hence the ability to cope with eating very different host plants appears to be an adaptation to this mode of dispersal.

    Chlenias auctaria
    male, drawing by Achille Guenée, Uranides et Phalénites
    ,
    Histoire naturelle des insectes; spécies général des lépidoptères,
    Volume 9, Part 10 (1857), plate 14, fig. 1,
    Image courtesy of Biodiversity Heritage Library, digitized by Smithsonian Libraries.

    The adult moths are grey with variable darker markings on the forewings.

    Chlenias auctaria
    female
    (Photo: copyright Dave Britton)

    Adult females do not fly very far from where they emerge from pupae, and lay large egg masses (around 200 eggs) on the top of plants. The eggs are oval and finely dimpled all over. They are initially white, but turn purple as they approach hatching.

    Chlenias auctaria
    eggs, magnified
    (Photo: copyright Cathy Young)

    The species is found in Queensland,

  • New South Wales,
  • Victoria,
  • Tasmania, and
  • South Australia.


    Further reading :

    Ian F.B. Common,
    Moths of Australia,
    Melbourne University Press, 1990, fig. 34.11, p. 364.

    Achille Guenée,
    Uranides et Phalénites,
    in Boisduval & Guenée:
    Histoire naturelle des insectes; spécies général des lépidoptères,
    Volume 9, Part 10 (1857), p. 239, No. 1315, and also plate 14, fig. 1.

    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 4 October 2010, 16 January 2016)