22 December 2012

Life History of the Banded Swallowtail

Life History of the Banded Swallowtail (Papilio demolion demolion)


Butterfly Biodata:
Genus: Papilio Linnaeus, 1758
Species: demolion
Cramer, 1776
Subspecies: demolion
Cramer, 1776VUWingspan of Adult Butterfly: 75-95mm
Caterpillar Host Plants: Luvunga crassifolia (Rutaceae), Luvunga scandens (Rutaceae), Melicope lunu-ankenda (Rutaceae).

A male Banded Swallowtail resting at a leaf perch.

A female Banded Swallowtail resting at a leaf perch.

Partial upperside views of the Banded Swallowtail showing one key difference (circled) between the two sexes.

Physical Description of Adult Butterfly:
Above, both sexes are black with a macular band of pale greenish spots extending from the forewing apex to the hindwing's mid-dorsum. The hindwing has a series of submarginal pale greenish lunules and a black tornal spot embedded in a much larger orange spot. The female has the inner half of the lunule in space 2 further coloured in orange (see above pic). Underneath, both sexes are similar with the macular band and submarginal lunules in the hindwing much broader and the area between them subdivided into two series of black spots by patches of orange and bluish-green scales. There is a moderately long spatulate black tail at end of vein 4 in the hindwing. Mirroring the difference in the hindwing upperside, the female has half of the submarginal lunule in space 2 coloured orange (see highlight A in below pic). The sinusoidal marginal black band is continuous in spaces 6 and 7 in the male, but broken in the female (see highlight B in below pic).

Partial underside views of the Banded Swallowtail showing two key differences (circled, marked A, B) between the two sexes.

A male Banded Swallowtail puddling on wet ground.

A puddling male Banded Swallowtail.

Another puddling male Banded Swallowtail.

Field Observations of Butterfly Behaviour:
Banded Swallowtail is moderately common in Singapore. The adults can be found in the nature reserves, wastelands, mangrove habitats and in offshore islands like Pulau Ubin and Pulau Tekong. The fast flying adults are frequently seen in flights along trails/tracks and while making occassional stops to visiting flowers growing in the surrounding vegetation. During cooler hours in early morning and late afternoon, adults could be found resting on leaf perches in an open wing manner. The males have been observed to puddle on wet grounds.



A Banded Swallowtail visiting flowers of a Syzygium plant.

A male Banded Swallowtail visiting Lantana flowers in a wasteland.

Early Stages:
The local host plants noted in recent breeding records are Luvunga crassifolia, Melicope luna-ankenda and Citrus spp., while Luvunga scandens was reported by Morrell in his 1957 paper in the Malayan Nature Journal. All these larval hosts belong to the Rutaceae family. The caterpillars of the Banded Swallowtail feed on leaves of the host plants, with those in early instars focusing on the young and tender leaves. They feed and rest in a gregarious manner in all 5 instars.

Local host plant #1: Luvunga crassifolia.

Local host plant #2: Melicope lunu-ankenda.

The eggs of the Banded Swallowtail are laid in a stacked manner, with varying number of eggs to each stack, either on a young shoot, a petiole or leaf surface of the host plant. Each yellowish egg is spherical with a diameter of about 1.1-1.2mm. The eggs are adhered to the substrate and to each other with a yellowish substance.

A female Banded Swallowtail laying its eggs in a stack on Melicope lunu-ankenda

A stick of 16 eggs of the Banded Swallowtail

A stick of 11 eggs of the Banded Swallowtail

Eggs of Banded Swallowtail. Left: 6 eggs; Right: 8 eggs.

Each egg takes about 3-4 days to hatch. The young caterpillar eats its way out of the mature egg, and then proceeds to finish up the rest of the egg shell. The emergence from eggs in the same stack is not synchronized in any particular order. Those emerging earlier and lower down the stack have been observed to not completely eating away the egg shell there, thereby avoiding the breaking of the stack. The whole stack is typically consumed fully by the group of newly hatcheds before they move on to their first leaf diet.

Left: Mature eggs. Right: newly hatched eating egg shells.

Each newly hatched is pale yellowish brown with a a body length of about 2.9mm-3mm. The head capsule is brown. On the body, there are two rows of short dorso-lateral tubular processes, each of which comes complete with a tuff of setae. Among these dorso-lateral processes, those on the prothorax, 8th and 9th abdominal segments are longer and larger. There are short lateral setae too.

Two views of a newly hatched caterpillar.

Two views of a 1st instar caterpillar, length: 4mm.

As the 1st instar caterpillar grows up to a length of about 6-6.5mm, the body colour becomes yellowish to orangy brown throughout with a faint green undertone. The body appears enlarged and broadened laterally in the 3rd thoracic and the 1st abdominal segments. After about 3 days in this 1st instar, the caterpillar moults to the next instar. Typically a few of them would stay dormant together prior to the moulting event, and the moulting times could stagger over a span of 1 day.

A group of 1st instar caterpillars, early in this stage.

A group of four 1st instar caterpillars, late in this stage, length: 6.5mm.

The 2nd instar caterpillar has a few changes in its appearance as compared to the 1st instar caterpillar. Now the lateral setae and setae on dorso-lateral processes are much shorter and inconspicuous to the naked eyes, whereas the dorsal-lateral processes on the prothorax and on the 9th abdominal segments are much longer proportionately. Each of the two dorso-lateral processes on the 8th abdominal segment now has an enlarged circular base, giving it a conical appearance. The head capsule has changed to the same yellowish/orangy brown coloration as that on the body segments. This instar lasts about 2.5-3 days with the body length reaching up to 10.5mm-11mm before the next moult.

Two views of a 2nd instar caterpillar, newly moulted, length: 7.5mm.

Dorsal views. Top: A late 2nd instar caterpillar, dormant prior to its moult. Bottom: A newly moulted 3rd instar caterpillar.

Lateral views. Top: A late 2nd instar caterpillar, dormant prior to its moult. Bottom: A newly moulted 3rd instar caterpillar.

The 3rd instar caterpillar resembles the 2nd instar caterpillar closely. One change, visible in the late 2nd instar caterpillar, is the presence of white dorso-lateral spots on the 1st , 4th, 5th, 6th abdominal segments and the 3rd thoracic segment, with additional white lateral spots on the 3rd thoracic and 6th abdominal segments. There are additional small dorso-lateral and lateral protuberances on the thoracic segments and the 1st abdominal segments. This instar takes about 3-4 days to complete with the body length reaching up to 19mm.

Two views of a 3rd instar caterpillar, length: 14mm.

Two views of a 3rd instar caterpillar, late in this stage, length: 19mm.

A group of Banded Swallowtail caterpillars, likely in 3rd instar, sighted duirng a field trip.

The 4th instar caterpillar resembles the 3rd instar caterpillar closely. The dorso-lateral processess on the 8th abdominal segment, prominent and conical in earlier instars, are now much reduced in size and no longer conical in appearance. Additional lateral white spots are also visible on the 1st abdominal segment. This penultimate instar lasts about 4-5 days with body length reaching about 27-29mm. On the last day of this instar, the body colour of the dormant caterpillar has a strong dark green undertone. Moreover, on its body, the bands and stripes due for the next instar are vaguely visible.

Two views of a 4th instar caterpillar, length: 25mm.

Two views of a 4th instar caterpillar, length: 29.5mm.

A group of 4th instar caterpillars.

Left: late L4 caterpillars, dormant prior to moulting. Right: early L5 caterpillars, newly moulted.

The next moult brings the caterpillar to its 5th and final instar with a drastic change in appearance. There are still dorso-lateral processes on the prothorax, 5th and 8th abdominal segments, but they are much shorter, inconspicuous and tubular in appearance. Among the newly introduced markings are two dorso-lateral dark eye spots at the leading edge of the 3rd thoracic segment. The eye spots are linked with a dark yellowish brown transverse band which has several embedded white spots. Another transverse band, bright yellowish brown in colour, can be found at the posterior edge of the same body segment. A similarly coloured oblique bar, embedded with dark brown patches and blue spots, stretches from the base of the 4th abdominal segment to the dorsum of the 5th abdominal segment. A much shorter version can be found in the 6th abdominal segment. After the moult to 5th instar, the body ground color is initially dark green, but this changes gradually to an attractive shade of turquoise within a few hours.

Two views of a 5th instar caterpillar, early in this instar, length: 33.5mm.

Two views of a 5th instar caterpillar, late in this stage, length: 41mm.

The 5th instar lasts for about 6-7 days, and the body length reaches up to 41-42mm. In the last 2-3 days, the body colour assumes a stronger green tone, and yellowish brown bands/stripes becomes much paler in colour tone, with some parts even turning whitish.

A group of late 5th instar caterpillars.

Two views of a 5th instar caterpillar, late in this stage, length: 42mm

As in the case of all Swallowtail butterflies, the Banded Swallowtail caterpillars in all instars and even the pre-pupal stage possess a fleshy organ called osmeterium in the prothoracic segment. The osmeterium is reddish brown in earlier instars but reddish to pinky red in the final instar. Usually hidden, the osmeterium can be everted to emit a foul-smelling secretion when the caterpillar is threatened.

The osmeterium of a pre-pupatory larva of the Banded Swallowtail.

Toward the end of the 5th instar, the body gradually shortens in length with the body base colour turning to bright green. Eventually the caterpillar comes to rest on the under surface of a stem or the petiole of a leaf. Here it stays dormant for a while before performing a purge of loose and wet frass pellets. It then spins a silk pad and a silk girdle to become an immobile pre-pupatory larva.

A pre-pupatory larva of the Banded Swallowtail. Left: early in this stage. Right: late, moments prior to pupation.

A Banded Swallowtail caterpillar molts to its pupal stage.

Pupation takes place a day later. The pupa suspends itself with a silk girdle from the substrate. There are two color forms. In the green form, the pupa is is mainly green with large yellowish green triangular patches on the dorsum of the abdominal segments. In the brown form, the pupa is mainly greyish brown with dark patches. Each pupa has a pair of cephalic horns and a dorsal thoracic hook-shaped process. The pupal body is angled in side view. Length of pupae: 31-32mm.

Lateral views of two forms of Banded Swallowtail pupae: brown form (top), green form (bottom).

Dorsal views of two forms of Banded Swallowtail pupae, brown form (left), green form(right).

  A green-form pupa of  Banded Swallowtail pupa observed in the field.

Three brown-form pupae of  Banded Swallowtail on the same branch.

After 12 days of development, the pupa turns black as the development within the pupal case comes to an end. The pale greenish band of spots on the forewing becomes visible through the pupal case. The next day the adult butterfly emerges from the pupal case.

A mature pupa of the Banded Swallowtail.

A Banded Swallowtail adult emerges from its pupal case.

A newly eclosed female Banded Swallowtail clinging onto its pupal case.

A newly eclosed male Banded Swallowtail clinging onto its pupal case.

References:
  • [C&P4] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society.
  • Butterflies of Thailand, Pisuth Ek-Amnuay, 2nd Edition, 2012
  • A Field Guide to the Butterflies of Singapore, Khew S.K., Ink On Paper Communications, 2010.
  • Miscellaneous notes on Malayan Butterflies, Morrell R., Malay. Nat. J. 11: 95-100, 1957.
Text by Horace Tan, Photos by Henry Koh, Goh Lai Choon, Mark Wong, Ellen  Tan,  Chng CK, Anthony Wong, Sunny Chir, Khew SK and Horace Tan

2 comments:

Aniruddha H D said...

Gorgeous butterfly and a really unique way of laying eggs!

Horace said...

Thanks, Aniruddha. :)
I thinks there is just a handful of species which oviposit in this manner.