Orchard Swallowtail Paul Balfe/Flickr

Orchard Swallowtail

Papilio aegeus

Did You Know?

Males can be territorial and will chase anything black and white that enters their territory, including Magpies
Considered a minor pest in citrus orchards, although unlikely to survive long in commercial orchards due to persistent spraying

The caterpillar (larva) is initially green, white and brown and resembles bird droppings. A mature caterpillar has a dark brown head, a green body with some pale yellow and brown markings, and spines along its back.

The male butterfly (adult) is black with an arc of creamy-white spots near the tip of each forewing. Each hindwing has a creamy-white patch and a single red spot, and there are many red crescents on its underside.

The female butterfly is brown to black, and the outer half of its forewing is whitish-grey. Its hindwing has a creamy-white patch, as well as a series of blue and red crescent-shaped markings.

Size

Caterpillar up to 6 cm long; Butterflies 10 – 12 cm wingspan.

Behaviour

Diet

The caterpillar eats the leaves of many plants, particularly citrus and native species from the Family Rutaceae; it prefers to eat young leaves but large caterpillars will eat older leaves. The butterfly feeds on nectar from a variety of plants, particularly lantana.

Movement

If disturbed, a caterpillar will reveal a red-orange “tentacle” (known as the osmeterium) from behind its head which emits a foul smell to deter predators.

Flight

Generally slow and erratic unless disturbed, and females fly more slowly during the egg-laying period. The males tend to “patrol” flight paths.

Breeding

Females lay eggs on the underside of host leaves, and the eggs hatch one week later.

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. The caterpillar eats for four weeks, then becomes a pupa for two weeks before emerging as a butterfly.

Where To Look

Along eastern Australia, from Cape York in northern Queensland to South Australia, but is rare in southern Victoria and South Australia as it prefers more humid tropical and subtropical conditions
In forests, woodlands and urban areas, including backyard gardens and orchards, particularly where citrus plants are grown
During periods of unusually high humidity it moves south during summer and autumn
Look on the leaves of citrus plants for caterpillars, and around flowers, particularly lantana, for butterflies

What Else?

Similar Species

Dingy or Dainty Swallowtail Butterfly caterpillar is smaller (about 3.5 cm long) and dark green to black with yellow and white spots. The butterfly is also smaller (6 cm wingspan) with creamy-grey patches over its entire black forewing, and creamy-white, red and blue patches on its hindwing.

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