13 February 2016

Life History of the Common Tiger

Life History of the Common Tiger (Danaus genutia genutia)


Butterfly Biodata:
Genus: Danaus Kluk, 1802
Species: genutia Cramer, 1779
Subspecies: genutia Cramer, 1779
Wingspan of Adult Butterfly: 70-80mm
Caterpillar Local Host Plants: Cynanchum ovalifolium (Apocynaceae), Cynanchum tunicatum (Apocynaceae).




Common Tiger form genutia.

Physical Description of Adult Butterfly:
On the upperside, the forewings are orange with a series of white spots in a broad, black apical border. The hindwings are either orange in form genutia or white with border tinged with orange in form intermedius. All veins on both fore- and hindwings are broadly marked with black. Marginal and submarginal series of small white spots are embedded in a black border at terminal margins of both wings. On the underside, the wings are similarly marked as per the upperside but with apical border orangey brown on the forewing

Common Tiger form intermedius.

Common Tiger form intermedius.

Common Tiger form genutia.

Field Observations of Butterfly Behaviour:
Both forms of the Common Tiger can be found in Singapore with form genutia being the more common of the two. This species is typically found in urban or sub-urban areas where its host plants are available. The adults typically visits flowers and has a fondness for sap exuded by Crotalaria spp.






Early Stages:
Locally, caterpillars of Common Tiger have been found to feed on leaves of two host plants in Apocynaceae: Cynanchum ovalifolium and Cynanchum tunicatum. Elsewhere in the region, Raphistemma spp. (Apocynaceae) have also been recorded as larval hosts in Malaysia and Thailand.

Local host plant #1: Cynanchum ovalifolium.

Local host plant #1: Cynanchum tunicatum.

The eggs of the Common Tiger are laid singly on the leaf of the host plant, typically on the underside. The milky white egg is shaped somewhat like a truncated rugby ball (diameter: 0.9mm, height: 1.3mm). The egg surface is ribbed with ridges running longitudinally. The micropyle sits atop.

A mating pair of Common Tiger.

An egg of the Common Tiger, height: 1.3mm.

The egg takes about 3 days to hatch. The young caterpillar emerges by eating away part of the egg shell. The rest of the egg shell becomes the first meal for the newly hatched, which has a length of about 2.6mm. Its whitish body has a fair number of short, black setae. The large head capsule is black in color and there is a small black patch at the posterior end. A pair of short sub-dorsal protuberances can be found on each of the following four segments: 1st and 2nd thoracic segments, 2nd and 8th abdominal segments. Of these, the prothoracic pair is black in color and the remaining pairs greyish. The thoracic legs are black in color.

Two views of a newly hatched caterpillar, eating its egg shell, length: 2.6mm.

Once the newly hatched moves on to feed on leaf lamina over the next few hours, its body starts to take on a green undertone. The growth is rather rapid with the body length doubling to about 4.8mm next day, and after just 1.5 days from hatching, it moults to the 2nd instar. Towards the second half of the 1st instar, the last three pairs of protuberances turn reddish brown and pairs of oval-shaped yellow spots, flanked by smaller reddish brown spots, appear on the dorsum from the 2nd thoracic segment to the 8th abdominal segment.

Two views of a 1st instar caterpillar, length: 4.2mm.

Two views of a late 1st instar caterpillar, dormant prior to its moult, length:4.8mm.

The body of the 2nd instar caterpillar is whitish in ground color. One obvious change is the lengthening of those black protuberances on the 2nd thoracic segment, 2nd and 8th abdominal segments. The pair of protuberances on the 1st thoracic segment remains subdued in size. A yellow band, interrupted by reddish brown spots, runs sub-spiracularly. The dorsal pairs of yellow spots are flanked by dark reddish brown spots which extend laterally to the subspiracular yellow band. The black head capsule now has a triangular white patch on the frons and two white arches. This instar lasts about 1 day with the body length reaching 7.6-8mm before the moult to the 3rd instar.

Two views of a newly moulted 2nd instar caterpillar.

Two views of a 2nd instar caterpillar, length: 7mm.

Two views of a late 2nd instar caterpillar, dormant prior to its moult, length: 7.6mm.

The 3rd instar caterpillar is similar in appearance to the 2nd instar caterpillar, One obvious change is in the three pairs of processes which are proportionately longer. This instar takes about 1.5 days to complete with body length reaching about 12mm.

Two views of a 3rd instar caterpillar, newly moulted, length: 7.5mm

Two views of a 3rd instar caterpillar, length: 10.4mm.

Two views of a late 3rd instar caterpillar, dormant prior to its moult, length: 11.6mm.

Retaining very much the same body features from the previous instar, the 4th instar caterpillar distinguishes itself in having proportionately longer processes, with the mesothoracic pair the longest and having a strong tendency to flex forward. The base of the first two pairs of processes exhibits a hint of red at this stage. This instar lasts about 1.5 days with the body length reaching about 22mm.

Two views of a 4th instar caterpillar, early in this stage, length: 13.5mm.

Two views of a 4th instar caterpillar, length: 20.8mm.

Two views of a late 4th instar caterpillar, dormant prior to its moult, length: 21.8mmmm.

The 5th and final instar caterpillar appears similar to the previous two instars except that all six processes now have a prominent crimson coloration at the basal portion. The sub-spiracular yellow band is broader and more prominent than in the earlier instars.

Two views of a newly moulted 5th instar caterpillar.

Two views of a 5th instar caterpillar, length: 34mm.

Two views of a 5th instar caterpillar, late in this stage, length: 38.5mm.

The 5th instar lasts about 2.5 days, and the body length reaches up to 39-41mm. On the last day, the caterpillar ceases feeding, and its body becomes shortened and decolorized. It wanders around in search of a pupation site. Typically it comes to a halt at a spot on the underside of a leaf, where the caterpillar spins a silk pad from which it soon hangs vertically to take on the pre-pupatory pose.

A pre-pupatory larva of the Common Tiger.

Pupation takes place about 0.5 days after the caterpillar assumes the hanging posture. The barrel-shaped pupa suspends itself from the silk pad with no supporting silk girdle. The greenish pupa has a median transverse series of connected silvery spots and a series of black dashes at the lower boundary of this transverse band. Length of pupa: 19-21mm.

Three views of a pupa of the Common Tiger.

Three views of a mature pupa of the Common Tiger.

After about 5 days of development, the pupal skin turns translucent as the development within the pupal case comes to an end. The prominent white spots and orange patches on the forewing upperside also become discernible. The following day, the adult butterfly emerges from the pupal case.


The eclosion event of a Common Tiger butterfly.

A newly eclosed Common Tiger 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, 1992.
  • Butterflies of Thailand, Pisuth Ek-Amnuay, 2nd Edition, 2012
  • A Field Guide to the Butterflies of Singapore, Khew S.K., Ink On Paper Communications, 2nd Edition, 2015.

Text by Horace Tan, Photos by James Chia, Bob Cheong, Mark wong, Anthony Wong, Simon Sng, Sunny Chir and Horace Tan

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