Life History of the Banded Royal

Life History of the Banded Royal (Rachana jalindra burbona)

Butterfly Biodata:
Genus: Rachana Eliot, 1978
Species: jalindra Horsfield, 1829
Subspecies: burbona Hewitson, 1878
Wingspan of Adult Butterfly: 30-34mm
Caterpillar Local Host Plant: Macrosolen cochinchinensis (Loranthaceae, common name: Common Chinese Mistleoe).

The underside of a male Banded Royal.

The upperside of a male Banded Royal.

Physical Description of Adult Butterfly:
On the upperside, the male is deep shining blue with black distal borders on both forewing and hindwing; the female is brown with black spots at the hindwing tornus and in space 2 surmounted by a narrow bluish grey area, and the black spots in spaces 1b and 2 lined with white patches. On the underside, both sexes are white with a broad brown distal border on both fore- and hindwings. A series of white-striae in the brown border separated it into two halves, with the outer half paler brown than the inner half. In the hindwing, there is a black tornal spot, a blush green patch in space 1b, a prominent orange-crowned black sub-marginal spot in space 2, and black post-discal striae in spaces 1b and 2. Each hindwing has a pair of black tails at ends of veins 1b and 2, with the one at vein 1b bordered with dense white cilia, and the one at vein 2 white-tipped.

The upperside of a female Banded Royal.

The underside of a female Banded Royal.

Field Observations:
The Banded Royal is rare in Singapore. It was only recently re-discovered in 2006 where a few individuals were sighted in an open area within the Central Catchment Nature Reserve. Since then, sightings of this species have mostly been confined to a few locations within the catchment nature reserve and in a western wasterland, and typically only a single individual appeared each time. The fast-flying adults have been sighted taking nectar at flowering plants.

Early Stages:
Across the distribution region of the Banded Royal, several plants in the Loranthaceae family have been identified as the larval hosts. In Singapore, thus far only one larval host plant has been identified. This local larval host is the Common Chinese Mistletoe (Macrosolen cochinchinensis ), a parasitic shrub with all parts of the plants glabrous (having no hairs, smooth). The leaves are leathery, opposite, ovate or lanceolate. On this plant, the early stages of the Banded Royal feed on the young leaves and developing fruits, with a strong preference for the latter.


Local host plant: Macroseolen cochinchinensis(Common Chinese Mistletoe).

A Banded Royal female laying an egg on a branch of the Chinese Mistletoe.

A freshly laid egg of the Banded Royal. Inset: an enlarged view of the egg.

Eggs are laid singly on the stem of the host plant, typically at the axil (angle/space between stem and branch, or between leaf and stem), or on a recess area or nook/crevice present on the stem. Each egg is about 0.8mm in diameter, white with a strong greenish tinge when freshly laid. It is bun-shaped with a depressed micropylar at the pole and a surface reticulated with rather large polygonal depressions.

Two vlews of an egg of the Banded Royal.

A fully developed egg with the caterpillar ready to emerge.

It takes about 3 days for the egg to hatch. The young caterpillar consumes just enough of the egg shell to emerge. It is pale yellowish brown in coloration, and has a length of about 1.1mm. Long setae (hairs) run along the length of the body dorsally as well as sub-spiracularly. Raised dorsal tubercles are transparent. A diamond-shaped black prothoracic shield is present. The 1st instar lasts about 3 days with the body length increased to about 2.1mm.

A newly hatched caterpillar next to its empty egg shell, length: 1.1mm.

Two views of a newly hatched caterpillar, length: 1.1mm.

Two views of a 1st instar caterpillar, length: 1.9mm.

A late 1st instar caterpillar of the Banded Royal, dormant prior to the moult to the next instar.

In the 2nd instar caterpillar, the dorsal tubercles are proportionately reduced in size, and the long dorsal setae seen in the 1st instar are now absent. The body base colour can either be reddish brown (red form) or green (green form). The caterpillar still features a black diamond-shaped prothoracic shield. The dorsum of the mesothorax and metamthorax are whitish, forming a prominent and trapezoidal patch. The dorsum of the 3rd to the 5th abdominal segements are also whitish, while that of the 1st, 2nd, 6th and 7th abdominal segements are dark reddish brown. The dorsal nectary organ is whitish and featured prominently on the dorsum of the 7th abdominal segment. The 2nd instar lasts for about 3 days, with the body length reaching up to 5.5-6.3mm.

A newly moulted 2nd instar caterpillar, eating its old skin.

Two views of a 2nd instar caterpillar of the Banded Royal, red form, length: 4.5mm.

Two views of 2nd instar caterpillar of the Banded Royal, green form, length:5.5mm.

Two views of a 2nd instar caterpillar, late in this stage, dormant prior to its moult, length:5.6mm.

In the 3rd instar, the markings on the dorsum of the caterpillar resemble those in the 2nd instar, but there is an additional pair of black dorso-lateral spots featured on the posterior segments. As in the 2nd instar, the body base colour can either be greenish or brownish. The dorsal nectary organ on the 7th abdominal segment and the tentacular organs on the 8th abdominla segment are now easily discernible.

Two views of a newly moulted 3rd instar caterpillar, eating its old skin.

Frontal view of a 3rd instar caterpillar, showing the black prothoracic shield, and the whitish patch on the mesothorax and metathorax.

Posterior segments of a 3rd instar caterpillar, showing the dorsal nectary organ on the 7th abdominal segment, and the tentacular organs on the 8th abdominal segment.

Two views of a 3rd instar caterpillar eating a developing fruit of the Chinese Mistletoe, with greenish body base colour, length: 7.5mm.

Two views of a 3rd instar caterpillar, with brownish body base colour, length: 10mm.

Two views of a 3rd instar caterpillar eating a developing fruit of the Chinese Mistletoe, with greenish body base colour, length: 11.5mm.

Two views of a 3rd instar caterpillar eating a developing fruit of the Chinese Mistletoe, with brownish body base colour, length: 12.5mm.

As the body grows to a length of around 12-13mm, the caterpillar stops feeding and comes to rest at a spot on the stem to prepare for the next moult. After about 3 days in the 3rd instar, the moult to the 4th and final instar takes place.

Two views of a late 3rd instar caterpillar, dormant prior to its moult to the final instar.

The 4th instar caterpillar resembles the 3rd instar caterpillar in most body features/markings, and is generally pale brown to greenish brown. In some individual specimens, the body colour can be mostly whitish in the abdominal segments. The prothoracic shield and the head are both black, as in the earlier instars. The 4th (and final) instar lasts about 5 days with the body length reaching up to 23mm.

Two views of a newly moulted 4th instar caterpillar, eating its old skin.

Frontal view of a 4th instar caterpillar, showing the black prothoracic shield, and the whitish patch on the mesothorax and metathorax.

Two views of a 4th instar caterpillar feeding on a developing fruit of the Chinese Mistletoe, length: 18mm.

Two views of a 4th instar caterpillar, length: 19mm.

Two views of a late 4th instar caterpillar, length: 23mm.

As it enters the pre-pupatory phase of its life cycle, the caterpillar ceases its feeding activity. Its body gradually shrinks in length and the colour turns pale brownish. The pre-pupatory caterpillar wanders around for up to 1-1.5 day in its quest for a suitable pupation site. Typically it settles for a spot on a surface which is partially concealed. At the chosen pupation site, it stays dormant for 1 day or so before spinning a silk pad to which it attaches itself via claspers at the posterior end.

Two views of a pre-pupa of the Banded Royal.


The pupation event for a Banded Royal caterpillar.

About 1 day after the pre-pupatory caterpillar secures itself to the pupation spot, pupation takes place. The pupa is held firmly via its cremaster to the silk pad on pupaton spot. It is 14.6 to 15.2mm in length, with the typical shape for a lycaenid pupa. It has a brown thorax with a whitish elongated dorsal patch on the mesothorax and metathorax, and pale yellow brown abdomihnal segments and brownish wing pads.

Two views of a pupa of the Banded Royal, length: 14.8mm.

Two views of a mature pupa of a female Banded Royal.

Two views of a mature pupa of a male Banded Royal.

Eleven to thirteen days later, the pupa becomes darkened in color signaling the imminent emergence of the adult. One can now tell the sex of the soon-to-emerge butterfly from the coloration of the wing pad at this stage (see pictures above). The next day the adult butterfly emerges from the mature pupa.


A female Banded Royal emerges from its pupal case.

A newly eclosed female Banded Royal resting next to 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 Loh Mei Yee, Lim Cheng Ai, Khew SK and Horace Tan

The Disappearing Acts 2

The Disappearing Acts 2

Now You See Me, Now You Don't

A No-Brand (or Small) Grass Yellow (Eurema brigitta senna) feeding on the flower of the Coat Buttons (Tridax procumbens)

In an earlier blogpost about some butterfly species that have been documented as extant species historically, we featured some species that appeared over a period of time, when several pristine individuals were seen for several weeks. Then for some mysterious reason, they disappeared altogether and not seen for many years. They appeared in very localised areas in Singapore, and may even be temporarily common, but have not been seen since.

A Pitcher Blue (Virachola kessuma deliochus) perched on the fruit of the Singapore Rhododendron (Melastoma malabathricum)

In this weekend's blogpost, we take a look at three extant species that are relatively small in size, and unlikely to be migratory or stray species in the local environment. However, after appearing for a short period of time, two of these species have not been spotted for many years thereafter. Having been recorded by the early authors, these species were not reliably recorded for many decades, until the period between 2006 and 2009, when two of these species were observed in very localised areas in Singapore.

A White Fourline Blue (Nacaduba angusta kerriana) perched on a leaf in the forest understorey

Then they disappeared, and were not seen for many years since. It is not known where they disappeared to in the meantime. As they are not all forest-dependent species, where do they go to? Perhaps in some localised area where they have not been spotted yet? Or do they have some sort of hibernation mechanism in their life-history biology that allows them to delay eclosion for a long time?

A female No-Brand Grass Yellow ovipositing on its host plant. Cassia mimosoides

Interestingly, when they appeared in Singapore, all their life histories were recorded on their respective caterpillar host plants. Their life histories are documented here on this blog. From the records that are shown here, their early stages are quite normal and there is nothing out of the ordinary that suggests that they have special characteristics compared to other butterflies.

1. The No-Brand (or Small) Grass Yellow (Eurema brigitta senna)

A female No-Brand Grass Yellow feeding on the flower of the Coat Buttons

The No-Brand Grass Yellow (also called Small Grass Yellow) was a recorded as a re-discovery in 2006 when it was spotted at an open patch of land in Punggol that was cleared for future development. Its caterpillar host plant, Cassia mimosoides grew wild as a "weed" in the area. For a period of about up to a year or so, the species was quite common at that site, and mingled with many of the urban and scrubland butterfly species.

A female No-Brand Grass Yellow ovipositing on its host plant, Cassia mimosoides

Today, a new public residential project is under construction at the site, and the open wasteland with secondary forest growth is no longer there. With that, the No-Brand Grass Yellow has disappeared. Efforts were made to cultivate its host plant in various places, and the caterpillars and pupae translocated to the other sites, but to no avail. The species has not been seen for a long time since then.

Upperside of the No-Brand Grass Yellow showing the scalloped black borders

A male No-Brand Grass Yellow perched on a leaf.  Note the heavily-speckled wings

The species looks very similar to many of its other Eurema cousins that are common all over Singapore. The main different on the upperside is that the black borders are regularly scalloped, unlike the deeply excavated black borders of the other species. On the underside, there are no cell spots, and the wings are heavily peppered with brown freckles all over. The underside of the female is more distinctive in that the hindwing is a paler yellow than the forewing.

2. The White Fourline Blue (Nacaduba angusta kerriana)

A White Fourline Blue perched on a leaf

The next feature species is a small butterfly with a wingspan of only about 30-35mm.  The White Fourline Blue was again, recorded as a re-discovery in 2009 at Telok Blangah Hill Park. It was a surprise as the species was documented as an extant species in Singapore by the early authors, but was not seen until 2009 - and even so, at an urban park. Was it one of the remnant species that survived despite the urban development in Singapore?

A mating pair of White Fourline Blues

When it appeared, there were several individuals fluttering around the shaded shrubbery, and we even encountered a mating pair of the species, suggesting that there was a small, but critically-endangered colony in that location. Fortunately, our life histories expert, Horace Tan, spotted a female ovipositing on its host plant, Entada spiralis and managed to document its life history successfully.

Upperside of a newly-eclosed female White Fourline Blue

The male White Fourline Blue is purplish blue above with a thin black border. The female has a broad black border on the forewing, and a light blue to whitish ground colour with diffuse greyish markings on both wings. The female is so distinctive that it cannot be confused with any other species in the Nacaduba genus. The underside is greyish ground colour with broad white diffuse markings. There is a prominent black rounded submarginal spot in space 6 of the hindwing.

3. The Pitcher Blue (Virachola kessuma deliochus)

A Pitcher Blue perched on the flower of the Coat Buttons

Unlike the preceding two species, the Pitcher Blue is an extant rare species that was re-discovered in the early 1990's at a site near the nature reserves in Chestnut Forest. It was subsequently spotted at Kent Ridge Park and other areas in the Southern Ridges. It was only until it was again observed at Bukit Batok Forest that its life history was recorded.

The species depends solely on the caterpillar host plants from the Nepenthes genus - commonly called Pitcher Plants or Monkey Cups. These plants prefer hilltops and rather dry, rocky areas to grow. Today, these plants are not common (due to habitat destruction and poaching) and this has possibly affected the survival of the Pitcher Blue. That the caterpillars feed inside the seed pods of the Pitcher Plant makes it even harder to survive without the plant, and the fact that the plant has to flower and fruit as well!

Upperside of a female Pitcher Blue

The male is a deep shining blue above with a broad black apical border on the forewing. The female is a light greyish-blue with narrower borders. The underside is grey with the typical white striae, resembling the Nacaduba species. The hindwing has a filamentous white-tipped tail at vein 2 of the hindwing. The Pitcher Blue is still occasional sighted, particularly at flowering trees like the Syzygium but sightings are erratic and it may not be seen for several years before another one turns up again.

Where are these species of butterflies today? Are they still lurking around somewhere, undiscovered, in some patch of greenery in our parks and nature reserves? Why have they disappeared for years on end? When will they reappear again? Answers to these questions continue to elude us as we strive on to struggle to further our knowledge and understanding of our butterflies to help conserve them for future generations.

Text by Khew SK : Photos by Khew SK and Horace Tan

Life Histories :

• No-Brand (Small) Grass Yellow 
• White Fourline Blue
• Pitcher Blue