Papilio anactus, commonly known as the Dainty Swallowtail, Dingy Swallowtail or Small Citrus Butterfly is a medium sized butterfly

Butterfly

A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...

 from the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Papilionidae, that is endemic to Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

.
For protection against predators, this non-poisonous butterfly mimic

Mimic

In evolutionary biology, mimicry is the similarity of one species to another which protects one or both. This similarity can be in appearance, behaviour, sound, scent and even location, with the mimics found in similar places to their models....

s the poisonous male Cressida cressida

Cressida cressida

The Clearwing Swallowtail or Big Greasy, Cressida cressida, is a medium-sized swallowtail butterfly found in Australia, Papua New Guinea and Indonesia. It is not a threatened species.-Description:...

, another swallowtail butterfly that obtains its toxic properties through its hostplant, the Dutchman's Pipe

Dutchman's Pipe

Dutchman's Pipe is a common name for some unrelated flowering plants, which have flowers, inflorescences or stems resembling a pipe:* Aristolochia species from the Aristolochiaceae...

.

Distribution

Papilio anactus is endemic to Australia, It originally came from New South Wales

New South Wales

New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

, Victoria

Victoria (Australia)

Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....

 and Queensland

Queensland

Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...

, but the growing of Citrus

Citrus

Citrus is a common term and genus of flowering plants in the rue family, Rutaceae. Citrus is believed to have originated in the part of Southeast Asia bordered by Northeastern India, Myanmar and the Yunnan province of China...

 orchards has caused the species to spread to South Australia

South Australia

South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...

 in the late 1920s. Papilio anactus is not present on Kangaroo Island

Kangaroo Island

Kangaroo Island is Australia's third-largest island after Tasmania and Melville Island. It is southwest of Adelaide at the entrance of Gulf St Vincent. Its closest point to the mainland is off Cape Jervis, on the tip of the Fleurieu Peninsula in the state of South Australia. The island is long...

 or Western Australia

Western Australia

Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...

 where there are currently insufficient citrus trees.

Its occurrence on New Caledonia is due to either an introduction, or as vagrants.

Life cycle

Eggs

The eggs are large, light yellow, roughly spherical. The eggs change to an orange color when the larvae are almost ready to emerge. Females only lay eggs on the newly grown leaves of the hostplant. They are laid at the edge of larger leaves, either above and beneath. The larvae develop inside the egg immediately after being laid. Eggs normally hatch in approximately 3–4 days but sometimes less depending on how late or early they're laid. The eggs are prone to small predators that eat the contents of the egg, and are also commonly parasitised by small wasps. Sometimes unfertilized eggs are laid.

Larva

The first instar is dark, with two rows of short, bristly spines. The anterior parts have broad yellowish bands, black head, with some short hairs, the first three instars retain this. Later instars have a white upside-down V mark on the front which becomes most visible in the last instar. The fleshy spines also become less bristly in later instars, and towards the last instar is almost absent. After emergence the immature larva eats the egg shell, before moving on to eat new leaf shoots. Later instars eat fully developed new leaves, but not usually matured leaves. In warm areas the larvae go through five instars, and larvae in cold areas can have six instars before developing to a pupa.

Mature larvae are about 35mm long, generally black, with two subdorsal rows of fleshy black spines, and sublateral and lateral rows of large orange or yellow blotches, and numerous small, light blue and white spots. The strength of yellow can vary, and some larvae can be a strong yellow or pale. The amount of orange can also vary, and it can be absent. There are subdorsal blue dots on the anterior part of the larva. The head is large, black, with a white upside-down V mark on the front.

When disturbed, the larvae can erect a reddish-orange coloured, osmeterium

Osmeterium

The osmeterium is a fleshy organ found in the prothoracic segment of larvae of Swallowtail butterflies including Birdwings. This organ emits smelly compounds believed to be pheromones. Normally hidden, this forked structure can be everted when the caterpillar is threatened, and used to emit a...

 from behind the head which releases a citrus-like smell of rotting oranges. This smell acts as a repellant to predators. The larvae attempt to throw their heads either backwards or sideways if a predator attacks because It is more effective if the chemical hits the predator. The secretion is usually composed of an irritant butyric acid

Butyric acid

Butyric acid , also known under the systematic name butanoic acid, is a carboxylic acid with the structural formula CH3CH2CH2-COOH. Salts and esters of butyric acid are known as butyrates or butanoates...

. The osmeterium is exists in all stages of the larvae.

Pupa

Straight, approximately 30 mm long. The thorax becomes notably out-stretching forward. It is usually attached to the stems of the hostplant and almost always on the other side of the tree from where the larva was last feeding. The larva will sometimes leave the hostplant to pupate. The pupa is attached to the stem by a central silken girdle. It either moves back vertically or is held horizontally. The colour is dimorphic, being either green or grey-brown with other variable markings. The colour pattern mimics the stem that the pupa is attached so that it looks like a snapped extension of the stem. If the stem is green or is surrounded by leafs, then the color of the pupa is mostly green. The time-span of the pupa can vary. It can be two weeks in summer

Summer

Summer is the warmest of the four temperate seasons, between spring and autumn. At the summer solstice, the days are longest and the nights are shortest, with day-length decreasing as the season progresses after the solstice...

, or up to four weeks in autumn

Autumn

Autumn is one of the four temperate seasons. Autumn marks the transition from summer into winter usually in September or March when the arrival of night becomes noticeably earlier....

. Often those pupae formed in autumn will not become adults until the following spring, or even longer with diapause

Diapause

Diapause is the delay in development in response to regularly and recurring periods of adverse environmental conditions. It is considered to be a physiological state of dormancy with very specific initiating and inhibiting conditions...

records of 1–2 years.