Plutella xylostella (Linnaeus, 1758)
Diamond Back or Cabbage Moth
(one synonym : Tinea cinerea Geoffroy, 1785)
Don Herbison-Evans
Stella Crossley

Plutella xylostella
(Photo: courtesy of Michael Keller, School of Agriculture and Wine, University of Adelaide, South Australia.)

This Caterpillar is a worldwide pest, and was unfortunately introduced into Australia by accident.

It is an agricultural pest on plants from the family BRASSICACEAE :

  • Chinese broccoli ( Brassica oleracea var. alboglabra ),
  • Cauliflower ( Brassica oleracea var. botrytis ),
  • Cabbage ( Brassica oleracea var. capitata ),
  • Brussel Sprouts, ( Brassica oleracea var. gemmifera ),
  • Broccoli ( Brassica oleracea var. italica ),
  • Chinese cabbage ( Brassica rapa var. pekinensis ),
  • Radish ( Raphanus sativus ),
  • Watercress ( Rorippa nasturtium-aquaticum ), and
  • Mustard ( Sinapsis alba ).

    Host plants also include several ornamentals, such as :

  • Wallflower ( Cheiranthus cheiri ),
  • Candytuft ( Iberis umbellata ),
  • Alyssum ( Lobularia maritima ), and
  • Stocks ( Matthiola longipetala ).

    An important reservoir for the species are various weeds, such as :

  • Wild mustard ( Sinapis arvensis ).

    Plutella xylostella
    cocoon and pupa
    (Photo: copyright Lyn Finn,
    Hunter Region School of Photography in Newcastle,
    Macquarie Hills, New South Wales)

    The caterpillar grows to a length of about 2 cms. It then pupates in an open mesh cocoon on a leaf of the foodplant.

    Plutella xylostella
    adult moth
    (Photo: courtesy of Donald Hobern, Aranda, Australian Capital Territory)

    The adult moth is brown with a pale zig-zag mark along the trailing edge of the fore wings. When the wings are closed, these create a series of diamond shapes along the back. It has a wingspan of about 1.5 cms. The pheromones of this species have been identified.

    Plutella xylostella
    (Photo: copyright Lyn Finn,
    Hunter Region School of Photography in Newcastle,
    Macquarie Hills, New South Wales)

    Internationally, it is a pest in:

  • France,
  • Hawaii,
  • India,
  • Japan,
  • United Kingdom, and
  • United States of America,
  • Venezuela,
  • Zimbabwe,

    as well as being occurring over the whole of Australia, including:

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

    This tiny moth is well-known for its migratory tendencies. Thousands have been counted in a single night crossing coastlines.

    Plutella xylostella
    (Photo: courtesy of Jean-Francois Landry, Ottawa Research and Development Centre)

    Attempts to control this pest have included:

  • use of acylurea growth regulators,
  • luring them with pheromones,
  • the bacterium Bacillus thuringiensis ( BACILLACEAE ) and associated toxins,
  • natural virus diseases,
  • extract of Neem seeds,
  • the larval-parasitoid wasp Diadegma insulare ( BRACONIDAE ),
  • the egg-parasitoid wasp Trichogramma chilonis ( TRICHOGRAMMATIDAE ),
  • the fungus Beauveria bassiana ( CLAVICIPITACAEAE ), and
  • breeding transgenic plants that are resistant.

    Plutella xylostella
    (Photo: copyright of Brett and Marie Smith, at Ellura Sanctuary, South Australia)

    Some confusing look-alikes are

  • Dialectica scalariella
  • Elachista flammula
  • Helcystogramma plutelliformis
  • Leptocroca sanguinolenta
  • Macrenches eurybatis
  • Monopis crocicapitella
  • Monopis ethelella

    Further reading :

    Ian F.B. Common,
    Moths of Australia,
    Melbourne University Press, 1990, fig. 21.7, p. 208.

    Carl Linnaeus,
    Insecta Lepidoptera,
    Systema Naturae,
    Volume 1, Edition 10 (1760), Class 5, Part 3, p. 538, No. 265.

    Peter B. McQuillan, Jan A. Forrest, David Keane, & Roger Grund,
    Caterpillars, moths, and their plants of Southern Australia,
    Butterfly Conservation South Australia Inc., Adelaide (2019), p. 45.

    Paul Zborowski and Ted Edwards,
    A Guide to Australian Moths, CSIRO Publishing, 2007, pp. 24, 61.

    Australian Butterflies
    Australian Moths

    (updated 31 October 2012, 17 April 2017, 13 October 2020, 5 December 2021)