Life History of the Common Birdwing (Troides helena cerberus)
Butterfly Biodata:
Genus: Troides Hübner, 1819
Species: helena Linnaeus, 1758
Subspecies: cerberus C&R Felder, 1865
Wingspan of Adult Butterfly: 100-140mm
Local Caterpillar Host Plant: Aristolochia acuminata (Aristolochiaceae, common name: Indian Birthwort, Dutchman's Pipe) .
A female Common Birdwing taking nectar from Ixora in an urban hill park
Ar female Common Birdwing taking nectar from Pagoda Flower in a nature park.
Physical Description of Adult Butterfly:
The forewings of both sexes are black with veins typically edged with greyish streaks, more conspicuously so in the female. The hindwings are rick golden yellow with black veins and black borders. In addition, the female has a complete series of rather large submarginal black spots, while the male has just one or a few submarginal spots.
A male Common Birdwing.
A female Common Birdwing.
Field Observations of Butterfly Behaviour:
The Common Birdwing is uncommon in Singapore, and is usually found where its host plants are cultivated. The adults are strong flyers and are capable of flying long distances and at considerable height in a bird-like manner. The adults have been sighted both in forested areas as well as in urban parks and gardens. As is the case for many of the Papilionidae species, an adult taking nectar from flowers can flutter its forewings whiles its hindwings are kept relatively still.
A female Common Birdwing taking nectar from flowers of an Acacia sp.
Early Stages:
The sole recorded local host plant, Aristolochia acuminata, is a perennial vine and can be found cultivated in various locations locally. In the wild, this plant can also be found in forests and open lowland thickets. The caterpillars of the Common Birdwing feed on the leaves and the young shoots of this plant.
Host plant : Aristolochia acuminata.
A mating pair of the Common Birdwing.
The eggs of the Common Birdwing are typically laid singly on the leaf surface or the stem of the host plant. It is however not uncommon that eggs are also laid on nearby natural objects or artificial structures. The spherical egg has its surface coated with a non-uniform layer of orange-yellow or whitish granulated substance. Diameter: 1.9-2.0mm.
Two views of an orange-colored egg of the Common Birdwing.
Two views of a white-coated egg of the Common Birdwing
A mature egg of the Common Birdwing showing the young caterpillar chipping away at the egg shell.
The egg takes about 6 days to hatch. The young caterpillar eats its way out of the mature egg, and then proceeds to devour the rest of the egg shell. The newly hatched is about 4.5-4.8mm long and has a black head, rows of short dorsal-lateral and lateral tubercles with tufts of short setae emanating from the terminal ends. It is mainly reddish brown with orange coloration on the anterior and posterior segments, and on the 4th abdominal segment.
A newly hatched caterpillar eating the egg shell.
Two views of a 1st instar caterpillar, newly hatched, length: 4.5mm.
After about 2-3 days in 1st instar, the caterpillar moults to the next instar.
Two views of a late 1st instar caterpillar, about to moult to the next instar, length: 8mm.
The 2nd instar caterpillar has a similar appearance to the 1st instar caterpillar except for the longer and fleshy processes, now devoid of the tufts of setae at their terminal ends. These fleshy dorso-lateral processes are colored in pinky or salmon red for those on 2nd-3rd thoracic, 4th abdominal and last 3 abdominal segments. The 2nd instar lasts 2-3 days and the body length reaches up to about 11mm before the next moult.
Two views of a 2nd instar caterpillar, early in this stage, length: 8.5mm
2nd instar caterpillar, late in this stage, length: 11mm
The 3rd instar brings about the appearance of a pale pinkish or whitish saddle straddling the 3rd-4th abdominal segments. This instar takes 2-3 days to complete with body grown to about 21mm in length.
Two views of a 3rd instar caterpillar, length: 19mm.
Two views of a late 3rd instar caterpillar, about to moult to the next instar, length: 20mm.
The 4th instar caterpillar has a more prominent saddle in pale yellowish brown or white coloration. extensive white markings on it body. The white patch on the posterior abdominal segments has extended to the whole of abdominal segment 7 and white lateral patches appear on the thoracic segments. This instar lasts about 4 days with body length reaching about 33mm.
Two views of a 4th instar caterpillar, early in this stage, length 22.5mm.
Two views of a 4th instar caterpillar, late in this stage, length 33mm.
The next moult brings the caterpillar to the 5th and final instar. Featuring the same layout of the fleshy processes, the body is uniformly colored in coffee brown to dark brown with the saddle mark painted in a comparatively lighter shade of greyish brown.
Two views of a a 5th instar caterpillar, late in this stage, length: 53mm.
A 5th instar caterpillar chomping away at a young stem in the field.
The 5th instar lasts for about 5 days, and the body length reaches up to 57-60mm. Toward the end of this instar, the body gradually shortens in length. Eventually the caterpillar comes to rest on the lower surface of a stem. It then goes on to spin a silk pad and a silk girdle to secure itself and becomes a non-mobile pre-pupatory larva.
A pre-pupatory larva of Common Birdwing.
All instars of the Common Birdwing possess a fleshy organ called osmeterium in the prothoracic segment. Usually hidden, the orange-coloured osmeterium can be everted to surprise any intruder when the caterpillar senses a threat.
Partially everted osmeterium of a final intar Common Birdwing caterpillar
The osmeterium can still be everted at the early pre-pupal stage.
Pupation takes place a day later. The upright pupa suspends itself with a silk girdle from the stem. with its cremaster attached to the silk pad at the lower end. The pupa resembles a rolled-up leaf with a length of about 43-45mm long. There are two colours form: green and brown.
A Common Birdwing caterpillar molts to its pupal stage.
Two colour forms of the Common Birdwing pupa. Dorsal views.
Two colour forms of the Common Birdwing pupa, side views.
After 19-20 days, the pupa turns black as the development within the pupal case draws to a close. The next morning the adult butterfly emerges from the pupal case.
A mature pupa of the Common Birdwing.
An eclosion sequence of the Common Birdwing.
A newly eclosed Common Birdwing clinging on to its empty 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, 1st Edition, 2006
