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  1. 38 Male by Leo Berzins
  2. 16_golden_sun_moth_synemon_plana_-_female_-_credit_to_leo_berzins Female by Leo Berzins

Golden Sun Moth

Synemon plana

Appearance

  • Colour: the male has dark brown forewings (front wings) with pale grey scales, and bronzy-brown hindwings with dark brown patches. The undersides of both wings are pale grey and black. The female has bright orange hindwings with black spots near the edge, while its forewings are similar to the male’s but more grey than brown. The underside of all its wings is white with small black spots near the edge. Both sexes have green eyes.
  • Its antennae are clubbed, with a knob at the end.
  • Size: the male has a wingspan of 3.4 cm, and the female has a wingspan of 3.1 cm 

Behaviour

  • Diet: the larva (caterpillar) feeds on the roots of native grasses, particularly wallaby grasses. The moth has no functional mouthparts and doesn’t eat at all.
  • Movement: the female rarely flies, unless it is disturbed, and tends to walk between tussocks of grass to lay eggs. The male spends its entire life flying, searching for females to mate with. It flies during the hottest part of bright sunny days, for about 6 – 8 weeks from November to January.
  • Flight: the male flies in a zig-zag pattern about one metre above the ground. The female has a smaller hindwing and is a very poor flyer.
  • Breeding: adult moths continuously emerge from underground tunnels throughout the flying season. The females possess fully developed eggs that are waiting to be fertilised by the male, and attract the males that are flying overhead by flashing their orange hindwings. After mating, the female lays up to 200 eggs at the base of wallaby grass tussocks. The eggs hatch after about 21 days and the larvae (caterpillars) then tunnel into the ground, where they live for one to three years. Adult moths live for only one to five days as they cannot eat. 

What to Observe

  • Presence (to establish the first and last sighting for the season)
  • Courting/mating
  • Mass flight or outbreak 

ClimateWatch Science Advisor

  • We expect moths to appear earlier in the year as a result of climate change warming the Earth.
  • There is a strong connection between emergence times and temperature, and over the past few years Golden Sun Moths have been observed flying about 14 days earlier than in the past (C Dwyer 2008, personal communication). 

When To Look

  • From October through to January
  • The flying season lasts 6 to 8 weeks (varies each year)
  • Look out for them on warm sunny days, during the hottest part of the day (typically between 10 am and 2 pm) 

Where To Look

  • In small, isolated remnants of native grasslands in south-eastern Australia, including south-eastern New South Wales, the Australian Capital Territory and Victoria.
  • In native open temperate grasslands and open grassy woodlands that are dominated by tussocks of wallaby grass (Austrodanthonia spp), spear grass (Austrostipa spp) or kangaroo grass (Themeda spp).

Golden Sun Moth Occurrence Map ALA

References

Common IFB 1990. Moths of Australia. Melbourne University Press, Carlton, Victoria. 

Kirkpatrick J, McDougall K and Hyde M 1995. Australia's Most Threatened Ecosystem: the southeastern lowland native grasslands. Surrey Beatty & Sons, Chipping Norton, Sydney.

O'Dwyer C 1999. The habitat of the Golden Sun Moth. In: W. Ponder & D. Lunney (eds.) The Other 99%: The Conservation and Biodiversity of Invertebrates, pp 322-324. The Zoological Society of New South Wales, Mosman.

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  1. Did You Know?

    The female’s poor flying ability and the male’s reluctance to travel any further than 100 metres from suitable habitat, mean that Golden Sun Moths cannot colonise sites more than 200 metres apart. Males on the wing could be dispersed by wind, but it is unlikely that any females would get that far.

    The variance in how long the larvae spend underground each year could be linked to the weather – they may stay underground longer to survive through harsh or less favourable years.

    Threats to the Golden Sun Moth’s survival include degredation, fragmentation and loss of its habitat through development, modifications to agricultural practices (such as fertiliser application) and invasion by weeds.