22 September 2012

Life History of the Perak Lascar

Life History of the Perak Lascar (Pantoporia paraka paraka)



Butterfly Biodata:
Genus: Pantoporia
Hübner, 1819
Species: paraka Butler, 1879
Subspecies: paraka
Butler, 1879
Wingspan of Adult Butterfly: 35-45mm
Caterpillar Local Host Plants:
Dalbergia candenatensis (Leguminosae), Dalbergia rostrata (Leguminosae), Cnestis palala (Connaraceae).




Physical Description of Adult Butterfly:
Above, the wings are dark brown to black with orange markings. On the forewing, there is a broad orange cell streak with two small indentations.  There are two orange submarginal lines on the forewing, one or both of which bends at  space 3.  The hindwing has a subbasal streak passing through base of cell, and a basal streak passing along costa. The dorsum of the thorax has a small yellowish green band aligned with the forewing cell streaks. Underneath, the wings have pale orange markings corresponding to those on the upperside, but generally larger, more diffuse  and edged in brown to black along some edges..These markings are set against a background in a shade of yellowish orange.



Field Observations of Butterfly Behaviour:  
This species is moderately common in Singapore.  It is more frequently found in back mangrove habitats (Sungei Buloh Wetland Reserve, Kranji nature trail, Pulau Ubin and Pulau Semakau) where its host plant,  Dalbergia candenatensis, thrives. The species can also be sighted, though less frequently, along forest trails in the nature reserve where its other host plant, Dalbergia rostrata,  is growing in small clusters on trail sides. The adults are weak flyers but are rather alert and skittish, and would quickly ascend to the tree top when alarmed. The adults have been sighted visiting flowers and puddling on wet ground, and would typically open their wings fully when perching.



Early Stages:
Of the three recorded local host plants for the Perak Lascar, two are Dalbergia species which are both relatively common in back mangrove habitats and in parts of the  nature reserve respectively. The third host plant, Cnestis palala (Connaraceae) which is relatively  rare in the nature reserve,  is also utilized by the immature stages of the Burmese Lascar.  

Local host plant #1: Dalbergia candenatensis.

Local host plant #2: Dalbergia rostrata.

Local host plant #3: Cnestis palala.

The caterpillars of the Perak Lascar feed on the young to middle-aged leaves of its host plants.  They typically feed in the open on the leaf surface, and rest on the midrib between feeds. The lamina of each leaf is usually eaten from the tip, leaving the midrib uneaten. But unlike the Athyma spp., there is no attempt to construct frass chain or frass barrier.  As in the case of Lasippa spp., the caterpillar of the Perak  Lascar in all instars has the habit of cutting rachis and petiole of the leaf it resides on and using silk threads to attach pieces of cut lamina to the exposed midrib. Its diet consists mostly of the brown and withered leaf lamina created in this process.

An early instar Perak Lascar caterpillar found on a leaf of Dalbergia rostrata in the nature reserve.

An early instar Perak Lascar caterpillar found on a leaf of Dalbergia candenatensis in Kranji nature trail.

The eggs of the Perak Lascar are laid singly at the tip of a leaf  or a budding young shoot of the host plant. The ovipositing female shares a common ovipositing routine adopted by a good number of  Nymphalidae species: After landing on a leaf and finding it suitable, the female reverses along the leaf surface, typically along the midrib, until its abdomen tip reaches the leaf tip where an egg is then deposited.

A mother Perak Lascar laying an egg at the leaf tip of a young leaf of Dalbergia rostrata.

Two views of an egg laid at a leaf tip. Diameter: 0.9mm.

The eggs are somewhat globular in shape, with surface marked with hexagonal pits and bearing spines at pit corners, giving them the appearance of minute sea-urchins. The micropylar sits atop. Freshly laid eggs are green in colour, but turning yellowish with rosy red patches when maturing. Each egg has a diameter of about 0.9mm. 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 2mm. It has a cylindrical pale greyish brown  body covered with many small tubercles and short setae. Four pairs of subdoral tubercles, found on the 2nd,  3rd thoraic segments and 2nd, 8th abdomnal segments,  are somewhat larger than the rest. The head capsule is similarly coloured but in a darker shade of brown.

Two views of a mature egg.

Two views of  a early 1st instar caterpillar, hours after it emerged from its egg., length: 2.2mm.

As the caterpillar grows, the body turns increasingly darker. The four pairs of subdorsal tubercles becomes more prominent. After reaching about 4.0mm in 2 days, the caterpillar moults to the 2nd instar.

Two views of a 1st instar caterpillar, late in this stage, length: 4mm.

The body color of the 2nd instar caterpillar is yellowish brown to reddish brown with a series of lateral oblique and inconspicuous streaks. Besides tiny tubercles covering most of its body surface, the 4 subdorsal pairs of tubercles have become longer and more spine-like with short protuberances. Furthermore, each of the two thoracic pairs of spines appear to  be connected with a slightly raised ridge between the two spines on each side. White strips are featured at the base of 8th and 9th abdominal segments. The head capsule is dark brown and dotted with a number of pale yellowish brown conical tubercles. This instar lasts about 3 days with the body length reaching about 5.5-6mm.

Two views of a 2nd instar caterpillar , length: 5.2mm.

The 3rd instar caterpillar has similar body markings as the 2nd instar  but with all  4 paris of subdorsal spines longer proportinately, and ridge connection in the two thoracic pairs more evident. A large saddle becomes apparent with a curved and tapering boundary taking shape, stretching from the base of the 2nd abdominal segment to a spot on the dorsum  of the 8th abdomnal segment between the two subdorsal spines.  This instar takes about 6-8 days to complete with body length reaching about 8-9mm.

Two views of a 3rd instar caterpillar, early in this stage, length: 6.5mm

Two views of a 3rd instar caterpillar, length: 9mm

The 4th instar caterpillar resembles the 3rd instar caterpillar closely. The oblique lateral brown streaks gain greater prominence with an increase in its shade of brown. A black lateral patch now appears  on the 6th abdominal segment, right on the boundary line of the saddle marking. The subdorsal pair of spines on the 8th abdominal segment are now the longest of all the subdoral spines, and are backward pointing as in the case for the pair on the 2nd abdominal segment.  This instar lasts about 8-9 days with the body length reaching about 12-13mm.

Two views of a newly moulted 4th instar caterpillar, length: 9.5mm.

Two views of a 4th instar caterpillar, late in this stage,dormant prior to its moult.

A 4th instar caterpillar found on its resident leaf in a back mangrove habitat.

Except from the proportionately increase in the length/size of the body and head capsule, the 5th instar caterpillar is little changed from the 4th instar in all body markings and features.


Two views of a newly moulted 5th instar caterpillar.


Two views of a 5th instar caterpillar feeding on withered leaf lamina, late in this stage, length: 17mm.

A 5th instar caterpillar found on a leaf in the field. The right panel contains a close-up view.

The duration of the 5th instar is rather variable, ranging from 10 days to 18 days in various bred specimens. The maximum body length is just as variable, with some only reach up only 17mm  and the longest ones up to 21mm.  On the last day, the color of the body decolorises slightly for some specimens, and none at all in others.  Typically, the fully grown caterpillar ceases feeding and stays dormant for a while. Then it proceeds to the tip of the midrib of a  eaten leaf, and spins a silk pad right at the tip. The caterpillar then turns around and attaches its claspers to the silk pad. From this head-up position, it  then gradually lets loose of its foot grip and in one short instant drops down to assume the hanging pre-pupatory posture. This particular `head-up drop' procedure is only adopted by a handful of Nymphalidae species.


A Perak Lascar caterpillar going through the chores of becoming a hanging pre-pupa.

Two views of a pre-pupa of the Perak Lascar.

Pupation takes place about 0.5 to a day later. The pupa suspends itself via a cremastral attachment to the silk pad at the leaf tip. It is almost entirely dark to rusty brown in color, with the ventral side of the head region and leading edge of the wing cases in a lighter shade of brown. The abdominal segments are  bent and tapering to the thin  and narrow cremaster at its posterior end. The wing cases are rather large and broaden laterally. The dorsum of the thorax is angular and is adorned with a number of silvery spots. The head is bluntly cleft at its front edge with small pointed lateral vertices. Length of pupae: 11-12mm.

Three views of a pupa of the Perak Lascar.

A pupa of the Perak Lascar found in the field.

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

Three views of a mature pupa. Orange markings on the forewings are now visible.


A Perak Lascar caterpillar emerges from its pupal case.


A newly eclosed Perak Lascar hanging on to its pupal case.


Another newly eclosed Perak Lascar hanging on to its pupal case.

References:

  • [C&P4] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, The Malayan Nature Society.
  • A Field Guide to the Butterflies of Singapore, Khew S K, Ink on Paper Comm. Pte. Ltd., 2010. 
  • Butterflies of Thailand, Pisuth EK-Amnuay, 1st Edition, 2006.
Text by Horace Tan, Photos by Benedict Tay,  Khew SK and Horace Tan

2 comments:

NickMorgan said...

Fabulous pictures as ever. How can a butterfly lay an egg like that? Does it form after it is laid? I have often wondered that with other eggs, but these eggs are really intricate.

Horace said...

Thanks, Nick for the kind words. :)
From what I read, butterflies' eggs with all their intricate features are already formed within the mother's body before the oviposition event.