Common Brown Butterfly Ed Dunens/Flickr

Common Brown Butterfly

Did You Know?

First recorded at Botany Bay, NSW in May 1770 during Captain Cook’s first voyage
Females delay laying their eggs until autumn rainfall to bring luscious fresh grass shoots for the caterpillars to eat

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

Caterpillar about 3.5 cm long; Butterfly wingspan 5.5 – 7.5 cm (females are larger than males).

Behaviour

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.

Field Guide

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What to Observe

Presence (to establish the first and last sighting for the season)
Courting/Mating
Egg laying
Chrysalis (butterfly emerging from its shell)

When and Where

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

What Else?

Similar Species

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 wing
Shouldered Brown (Heteronympha penelope) has darker markings near the wing bases giving it a shouldered look, and an extra eyespot on the hindwin
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

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