Common Brown Butterfly
- Colour: the caterpillar (larva) is initially a pale yellow-grey, before turning green with long black hairs along its body. Its head is brown-black with short hairs. The female butterfly (adult) is orange with creamy yellow and dark brown patches towards the tip of its forewings (front wings). The male is less colourful, being brown and orange with no pale patches. It also has an obvious raised vein in the middle of its forewing. Both males and females have a small eye-spot on each wing. The undersides of the wings in both the male and female are paler with faint markings, and their hindwings have very few markings. The female’s hindwing is darker then its forewing. It is difficult to identify these butterflies when they are resting with their wings closed.
- The males emerge quite a while earlier in the year before the females.
- Size: the caterpillar is about 3.5 cm long; the butterfly has a wingspan of 5.5 – 7.5 cm (females are larger than males).
- Diet: the caterpillar eats various native and introduced grasses, while the butterfly drinks nectar from flowers. The butterflies are also attracted to fermenting fruit and gum seeping from tree wounds.
- Movement: when a caterpillar is disturbed while feeding, it drops to the ground and lies still. When male butterflies are not feeding, they fly close to the ground looking for females. If disturbed, a female butterfly will reject the male by lying on the ground with her wings closed. Butterflies fly from October to May, depending on the area and elevation; they emerge later in higher and cooler areas. There is a predominance of males in the earlier part of the season and females in the later part.
- Flight: irregular, these butterflies prefer to settle on or near the ground.
- Breeding: mating occurs from October to December, after which the males die. The females rest through summer (known as aestivation) and appear again in late February to early May to lay their small, pale yellow eggs on the underside of leaves. The females die shortly after laying the eggs and the caterpillars hatch from the eggs after about 12 days.
What to Observe
- Presence (to establish the first and last sighting for the season)
- Egg laying
- Chrysalis (butterfly emerging from its shell)
ClimateWatch Science Advisor
We expect butterflies to appear earlier in the year as a result of climate change warming the Earth. They may also start appearing in new areas as warmer temperatures enable them to live in environments that were previously too cold for them.
When To Look
- From October through to May for butterflies.
- From June to August for caterpillars.
- Mating occurs from October to December.
- Females re-emerge to lay eggs from late February to early May.
- On hot days look out for them in the early morning and late afternoon.
Where To Look
- In eastern Australia from central Queensland to the Flinders Ranges and Eyre Peninsula in South Australia, including Tasmania. Also in south-west Western Australia.
- In temperate regions in open forests and woodlands that contain grass; also in urban areas.
- Look in grasses (for caterpillars and butterflies) and also around flowers for butterflies.
- They are attracted to garden sprinklers on hot days and are common in urban gardens.
The map below displays the accumulated observations of these species as reported by ClimateWatch observers, together with the layer showing how the range of the species might change between now and 2085, with orange areas indicating where the species might disappear, and green areas where the species range might expand.
Braby MF 2000. Butterflies of Australia: Their Identification, Biology and Distribution. CSIRO Publishing.
Common, IFB and Waterhouse, DF 1981. Butterflies of Australia (revised edition). Angus & Robertson.
- Banks Brown Butterfly (Heteronympha banksii banksii): has an eyespot only on its hindwings, not on all wings.
- Wonder Brown Butterfly (Heteronympha mirifica): the female doesn’t have any orange colouring and the male doesn’t have an eyespot on the underside of its wings.
- Shouldered Brown (Heteronympha penelope): has darker markings near the wing bases giving it a shouldered look, and an extra eyespot on the hindwing.
- Bright-eyed Brown Butterfly (Heteronympha cordace): has more black markings on its upperside, an extra eyespot on its hindwing and more markings on the underside of its hindwings Spotted Brown Butterfly (Heteronympha paradelpha paradelpha): has more black markings on its upperside and an extra eyespot on its hindwing.
- Solander’s Brown Butterfly (Heteronympha solandri): has more black markings on its upperside.
- Forest Brown or Cyril's Brown Butterfly (Argynnina cyrila): has more black markings on its upperside.
Did You Know?
The Common Brown Butterfly was first recorded at Botany Bay, NSW in May 1770 during Captain Cook’s first voyage.
Females delay laying their eggs until there has been some autumn rainfall to bring luscious fresh grass shoots for the caterpillars to eat.