Danaus plexippus (Linnaeus, 1758)
Wanderer or Monarch
Don Herbison-Evans
Stella Crossley

Danaus plexippus

The eggs of this species are bottle-shaped and pale yellow, laid singly on the undersides of the leaves of the foodplant.

Danaus plexippus
(Photo: courtesy of Mike Belgrove, Eaton, Western Australia)

At first the Caterpillar is cream with a black head. Later the caterpillar develops yellow, white and black rings circling the whole length of its body. It also develops two pairs of black tentacles protruding from its back: a long pair on its mesothorax, and a shorter pair on its eighth abdominal segment. These tentacles are soft and in no way dangerous.

In Australia, its foodplants are all from the Milkweed family (APOCYNACEAE), including :

  • Moth Plant ( Araujia hortorum ),
  • Blood Flower ( Asclepias curassavica ),
  • Balloon Plant ( Asclepias physocarpa ),
  • Common Milkweed ( Asclepias syriaca ),
  • Mudar Plant ( Calotropis gigantea ),
  • Wild Cotton ( Gomphocarpus cancellatus ),
  • Swan Plant ( Gomphocarpus fruticosus ),
  • Carrion Plant ( Stapelia grandiflora ), and
  • Starfish Cactus ( Stapelia variegata ).

    Danaus plexippus
    "life hanging by a thread"
    caterpillar attacked by a Shield Bug
    (Photo: courtesy of Tony Bailey, Arundel, Queensland)

    The caterpillar's foodplants all have a poisonous milky sap. The caterpillar appears to retain the poisons in its body which were thought to make it unpalatable to predators, although this is evidently sometimes ineffective.

    Danaus plexippus
    (Photo : courtesy of Fred Swindley, Meadowbank, New South Wales)

    It pupates hanging by its tail-like cremaster on the stem or leaf of its foodplant. The pupa is green with a band of shiny gold spots extending half way around it. After about three weeks in summer the adult emerges.

    Danaus plexippus
    (Photo : courtesy of Fred Swindley, Meadowbank, New South Wales)

    The adult butterfly is orange-brown, with black veins and a black and white spotted band all around the wing margins. The upper and lower surfaces of the wings are similar, except that the undersides of the hindwings are more yellowish.

    Danaus plexippus
    (Photo : courtesy of Fred Swindley, Meadowbank, New South Wales)

    The main difference between the male and female butterflies is that the males have a 'sex mark' on the hindwing. This looks like a swelling in one of the veins which runs from the discal cell to the margin.

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

    Females also tend to have broader black veins than the males. The wingspan is about 9 cms.

    Danaus plexippus
    Grenadines of St. Vincent, 1975

    This species is only a recent arrival in Australia. The earliest report is dated 1856 in Sydney. A drawing dated 1878 done in Sydney is held by the State Library of Tasmania. The species was originally from America. It reached Hawaii in 1845, and England in 1876.

    In America, the adult butterflies perform extensive migrations to equable areas in which to pass the winter. Populations in the North-West migrate to Monterey in California to overwinter. The overwintering grounds of the Eastern populations were only discovered in 1975, when they were located in a mountain area in Mexico. This was the climax of four decades of research by Dr. Fred Urquhart (National Geographic Magazine, Vol. 150, No. 2, August 1976). Similar research involving the release of marked butterflies has been carried out by the Australian Museum in Sydney, to investigate possible migrations in Australia.

    The butterflies have been found to navigate using how the sunshines on the antennae. If one antenna is painted black, they act disoriented.

    Danaus plexippus
    (Photo: courtesy of Kath Vail, Inner Pocket, New South Wales)

    The species may be found all over the world, including:

  • Europe,
  • Hawaii,
  • North America,
  • New Zealand,

    and in all of Australia, including :

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

    Danaus plexippus
    Aruba, 1986

    The species is featured at the Coffs Harbour Butterfly House.
    Butterflies of this species may be purchased for release at weddings etc, from various breeders including:

  • Butterfly Adventures (Carnegie, Victoria)
  • Butterfly Encounters (Brisbane), and
  • Butterfly Karma (Melbourne).

    The caterpillars have many enemies. One is Ophryocystis elektroscirrha which is a protozoan parasite. Caterpillars feeding on Wild Cotton ( Gomphocarpus cancellatus ) seem better protected against this parasite, possibly because the plant contains higher concentrations of cardenolide glycosides.

    Danaus plexippus
    (Courtesy : Instant Scratch-Its)

    Further reading :

    Michael F. Braby,
    Butterflies of Australia,
    CSIRO Publishing, Melbourne 2000, vol. 2, pp. 597-598.

    Frank Jordan & Helen Schwencke,
    Create More Butterflies : a guide to 48 butterflies and their host-plants
    Earthling Enterprises, Brisbane, 2005, p. 32.

    Carl Linnaeus,
    Insecta Lepidoptera,
    Systema Naturae,
    Volume 1, Edition 10 (1760), Class 5, Part 3, p. 471, No. 80.

    Australian Butterflies
    Australian Moths

    (updated 20 July 2012, 6 January 2018)