22 May 2011

Life History of the Blue Pansy

LIfe History of the Blue Pansy (Junonia orithya wallacei)



Butterfly Biodata:

Genus: Junonia
Hübner, 1819
Species: orithya Linnaeus, 1758
Subspecies: wallacei Distant, 1883
Wingspan of Adult Butterfly: 40-55mm
Caterpillar Local Host Plant: Asystasia gangetica (Acanthaceae)



A Blue Pansy perching on a flower giving a view of its wing underside.


A sunbathing female Blue Pansy showing its wing upperside.

Physical Description of Adult Butterfly:
Above, the forewing for the male is black to dark brown with a whitish sub-apical band, two orange and two blue bars in the cell, and two post-discal eye-spots in spaces 2 and 5. The hindwing of the male is brilliant blue with orange post-discal eye-spots in spaces 2 and 5. In some specimens, the eye-spot in space 5 is much reduced in size and black in colour. The female is similarly marked but with a much duller hue. Underneath, both sexes are grayish brown with cryptic orange/brown markings and have eye-spots similarly placed as on the upperside.


A sunbathing male Blue Pansy displaying its upperside.


Another female Blue Pansy.


Field Observations of Butterfly Behaviour: This species is relatively common in Singapore, although much less so than its cousins, the Chocolate Pansy and the Peacock Pansy. The adults can be occasionally be found in parks and gardens, but more often in open grassy wastelands. They tend to visit tiny flowers growing in grassy areas, and sunbathe with wings fully open. The flight is rapid and typically done in a gliding fashion.


A female Blue Pansy.



A newly eclosed female Blue Pansy with a view of its wing underside.

Early Stages:
The caterpillars of the Blue Pansy feed mainly on leaves of its local host plant, Asystasia gangetica, which is a very common weed in wastelands, fringes of nature reserves and strips of land left untended for a period of time.


Local host plant: Asystasia gangetica.

A mother Blue Pansy laying an egg on flower buds.

The eggs of the Blue Pansy are laid singly on the young leaves or shoots of the host plant or other plants in the vicinity. The greenish egg is somewhat globular in shape but with a blunt top. Twelve raised ridges run from this top end to the base of the egg. Each egg has a diameter of about 0.6-0.7mm.


Two views of an egg of the Blue Pansy. Diameter: 0.6-0.7mm.

Two views of a mature egg of the Blue Pansy.

The egg takes about 2.5-3 days to hatch. The young caterpillar emerges by making an exit by eating away part of the egg shell. The rest of the egg shell becomes the first meal for the caterpillar. The initial length of the newly hatched is about 1.3mm. The
cylindrical and pale yellowish green body is covered with many small dark-colored tubercles. Long dark setae emanate from those tubercles occurring dorso-laterally and laterally. The head capsule is black.


Two views of a newly hatched caterpillar, length: 1.3mm.

The 1st instar caterpillar feeds on the lamina of young leaves and it has a preference for the very young leaves of an emerging shoot. After reaching about 3mm in 2-3 days, the caterpillar moults to the 2nd instar.


Two views of a 1st instar caterpillar, late in this stage, length: 3mm.

The body of the 2nd instar caterpillar is mostly dark brown on all segments except for the prothoracic segment which is orange in color. Moderately long and branched dark brownish processes run along the length of the body. Fine setae emanate from these processes and from other small tubercles on the body surface. The head capsule is still entirely black. This instar lasts about 2-2.5 days with the body length reaching about 5mm.


Two views of a 2nd instar caterpillar, newly moulted, length: 2.9mm


Two views of a 2nd instar caterpillar, late in this stage, length: 5mm

The 3rd instar caterpillar has proportionately longer dorso-lateral and lateral processes which are dark brown to black in color as is the case for the body ground colour. This instar takes about 2 days to complete with body length reaching about 9.5mm.


Two views of a 3rd instar caterpillar, early in this stage, length: 6mm.


Two views of a 3rd instar caterpillar, length: 8mm.

The 4th instar caterpillar closely resembles the 3rd instar caterpillar, except for the proportionately longer body processes and the change to orange color for the frons at the front of the head capsule. The 4th instar lasts about 3 days with the body length reaching about 13mm.


Two views of a 4th instar caterpillar, length: 11mm.


An agitated 4th instar caterpillar displaying its kung-fu stance, length: 11mm.
Two views of a 4th instar caterpillar, late in this stage, length: 13mm. Inset: head capsule.

The 5th (and penultimate) instar caterpillar is similar to the 4th instar caterpillar. One discernible difference is in the head capsule which has an expanded presence of orange markings on the lateral and top sides. Two small and short black apical cephalic horns are now easily discernible. This instar lasts for about 3 days, and the body length increases rather dramatically and reaches up to 22.5mm. As it lies dormant prior to its moult, lateral orange markings appear at the base of various tubercles.


A 5th instar caterpillar, early in this stage, length: 13mm. Inset: head capsule.


Two views of a 5th instar caterpillar, late in this stage, length: 22.5mm.


A late 5th instar caterpillar in a dormant stage prior to the moult to the next instar.

The 6th (and final) instar caterpillar is structurally similar to the 5th instar caterpillar but with several changes in markings and coloration. Now the body processes are black with a bluish sheen. The base of the sub-spiracular row of tubercles are orange, and are linked with a series of intermittent white streaks. The lateral row of tubercles are lined with white streaks on most of the abdominal segments. The head capsule is now mostly orange and has two small black patches flanking the frons.


Two views of a 6th instar caterpillar, length: 31.5mm.


Two views of a 6th instar caterpillar, late in this stage, length: 44mm.


A 6th instar caterpillar found in the field on its host plant.

The 6th instar lasts for 4-5 days, and the body length reaches up to 45mm. The caterpillar ceases feeding and wanders around. Eventually it stops at a spot on the underside of a leaf, young shoot/stem and spins a silk pad from which it hangs vertically to take on the pre-pupatory pose.


A pre-pupa of the Blue Pansy.


The pupation event of a Blue Pansy caterpillar.

Pupation takes place about 0.5 days later. The pupa suspends itself from the silk pad with no supporting silk girdle. It is mainly dark brown, but pale brown in wing pads and on the ventrum. Whitish bands runs on the dorsum near the cremaster and mid-abdomen. There is a series of dorso-lateral pairs of very short and pointed processes, one pair to each segment. The dorsum is slightly raised at the mesothorax. Length of pupae: 17-19mm.


Three views of a pupa of the Blue Pansy.


Three views of a mature pupa of the Blue Pansy.

After about 6 days of development, the pupal skin of the mature pupa turns translucent and the pupa turns dark brown to black as a result. Patches of orangy brown can also be noticed in the wing pad. The adult butterfly emerges from the pupa the next day.


The eclosion event of a Blue Pansy caterpillar.


A newly eclosed Blue Pansy resting on 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, 1st Edition, 2006
  • A Field Guide to the Butterflies of Singapore, Khew S.K., Ink On Paper Communications, 2010.
Text by Horace Tan, Photos by James Chia, Simon Sng, Sum Chee Meng, Federick Ho, Khew S K and Horace Tan

1 comment:

Callixa said...

I just raised one of these :)