Life History of the White Banded Flat

Life History of the White Banded Flat (Celaenorrhinus asmara asmara)

Butterfly Biodata:
Genus: Celaenorrhinus Hübner, 1819
Species: asmara Butler, 1879
Sub-species: asmara Butler, 1879
Wingspan of Adult Butterfly: 40mm
Caterpillar Local Host Plant: Jasminum elongatum (Oleaceae, common names: Common Malayan Jasmine, 扭肚藤).

A male White Banded Flat.

Physical Description of Adult Butterfly:

On the upperside, the wings are brown. On the forewing, there are hyaline subapical spots in each of spaces 6,7 and 8. There is also an oblique discal band extending from cell-end to vein 2. On the hindwing, there are some obscure darker brown markings. Underneath, the wings are similarly marked as per above. The male has erectile hair tuft on the hind tibia which gives the legs a rather hairy appearance.

A female White Banded Flat.

Field Observations of Butterfly Behaviour:  
This species is rare in Singapore and its distribution is restricted to a few areas in the offshore island of Pulau Ubin. A small colony was rediscovered in 2011, and since then sightings have been very infrequent. As is the case for the Tagiades species, the adults have the habit of perching on the underside of a leaf between flights, and with its wings opened flat. The adults are also active only during the few hours after sunrise.

Early Stages:
To date only one local host plant, Jasminum elongatum, has been recorded for the White Banded Flat. This plant can be found growing at a few sites on Pulau Ubin, as well as being cultivated in multiple parks and gardens on the main island. Outside Singapore, Clerodendrum fragrans has also been recorded as the larval host. The caterpillars of the White Banded Flat feed on leaves of the host plant. When not feeding, the caterpillars seek  safety and concealment in a leaf shelter formed  by cutting and folding a leaf fragment along the edge of the leaf.

Local host plant: Jasminum elongatum.

The eggs of the White Banded Flat are laid singly on the underside of a leaf of the host plant. At times, several eggs can be found on different parts of the same leaf as a result of different oviposition visits by the same or different female. The whitish egg is hemispherical with surface marked with longitudinal ridges running from the pole to the rim of the base. Each egg has a basal diameter of about 1mm.

An egg of the White Banded Flat found on the underside of a leaf of the host plant.

Two views of an egg of the White Banded Flat.

The egg takes about 5 days to hatch. The young caterpillar emerges by eating away the polar  part of the egg shell. The rest of the egg shell is not eaten by the newly hatched which is about 2.2-2.3mm in length. The yellowish body is roughly cylindrical in shape and the head capsule is black or dark reddish brown in color. A prominent, black collar mark is present on the dorsum of the prothorax.

Left: mature egg. Right: empty egg shell.

Two views of a  newly hatched caterpillar of White Banded Flat cutting leaf lamina for its first leaf shelter, length: 2.3mm.

The newly hatched makes its way to the leaf edge to  construct its very first  leaf shelter right away. Typically the cut-out leaf fragment is turned over and secured to the upperside of the leaf. The caterpillar ventures out of the shelter from time to time to feed on the leaf lamina in the vicinity. As the caterpillar grows, the body assumes a green undertone. After reaching about 5mm in about 4-4.5 days, the caterpillar moults to the 2nd instar.

Top: a newly hatched caterpillar cutting the leaf lamina. Bottom: the completed leaf shelter with the cut-out folded over.

Two views of a 1st instar caterpillar of the White Banded Flat, length: 3mm.

Two views of late 1st instar caterpillar of the White Banded Flat, dormant prior to its moult to the next instar.

The body of the 2nd instar caterpillar is pale whitish to yellowish with a green undertone. There is no trace of the black collar mark on the prothorax seen in the 1st instar. The head is black and broadened sideways to two short tips at the upper end. The surface of the body is sparsely dotted with tiny whitish setae. This instar lasts about 5-5.5 days with the body length reaching about 8mm.

Two views of a 2nd instar caterpillar of the White Banded Flat, early in this stage, length: 4.5mm.

Two views of a 2nd instar caterpillar of the White Banded Flat, length: 6.5mm.

Two views of a late 2nd instar caterpillar of the White Banded Flat, dormant prior to its moult.

The 3rd instar caterpillar closely resembles the 2nd instar caterpillar. The head capsule is dark reddish brown but broader sideways and with the two raised tips more prominent. This instar takes about 5.5-6 days to complete with body length reaching about 12-13mm.

Two views of a 3rd instar caterpillar of the White Banded Flat, early in this stage, length: 7.5mm.

Two views of a 3rd instar caterpillar of the White Banded Flat, length: 9mm.

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

The 4th instar caterpillar is little changed from the 3rd instar in all body features. The head capsule is reddish brown soon after the moult, but turned dark reddish brown moments later. This penultimate instar lasts about 7.5-8.5 days with body length reaching about 20mm.

Two views of a 4th instar caterpillar of the White Banded Flat, early in this instar.

Two views of a 4th instar caterpillar of the White Banded Flat, length: 16mm.

Two views of a 4th instar caterpillar of the White Banded Flat, length: 19.5mm.

A leaf shelter of a 4th instar caterpillar of the White Banded Flat (top right leaf) sighted in the wild.

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

The 5th instar caterpillar has similar body markings as in the 4th instar initially. As in the 4th instar, the head capsule is bright reddish brown after the moult, but turning dark reddish brown moments later. As growth progresses in this instar, a thin yellowish lateral band appears on each side of the body. In this instar, and sometimes in the 4th instar, the leaf shelter is constructed from joining two adjacent leaves together. The 5th instar lasts for about 8-9 days, and the body length reaches up to 28-29mm.

Two views of a 5th instar caterpillar of the White Banded Flat, newly moulted with exuvia nearby.

Two views of a 5th instar female caterpillar of the White Banded Flat, late in this stage, length:28mm.

Two views of a 5th instar male caterpillar of the White Banded Flat, late in this stage, length:28mm. Note the pair of testes visible on the dorsum.

On the last day of 5th instar, the body decolorises  to a very pale whitish shade of yellowish green. The caterpillar ceases feeding and confines itself to the leaf shelter. The pre-pupatory larva prepares for the pupal phase with a series of silk construction work with the main pieces being a silk girdle across the dorsum of its early abdominal segments, and a short and thickened transverse silk band on the substrate at its posterior end. Soon the pre-pupatory larva becomes dormant in its leaf shelter. Pupation takes place about 1 day later.

A pre-pupa of the White Banded Flat seen through the side of the partially opened leaf shelter.

The girdled pupa is secured with its cremaster attached to the short transverse band on the substrate. It has a short thorax, a rather long abdomen, a pointed brown rostrum and two lateral brown cephalic processes. The body is pale whitish beige brown in the abdomen but yellowish green in the thorax and wing pads. There are two brownish patches on the upper part of the wing pad. The ventrum of the thorax has a remarkable convex downward outline. Length of pupae: 22mm.

Two views of a pupa of the White Banded Flat.

After about 6.5-7 days of pupal development, the pupal turns dark in the wing pad and thorax areas. The white discal band is also visible at this time. The following day, the adult butterfly emerges from the pupal case.

Two views of a mature pupa of the White Banded Flat.

A newly eclosed female White Banded Flat.

A newly eclosed female White Banded Flat, resting next to its pupal case.

A newly eclosed male White Banded Flat, resting atop its pupal case.

References:

• [C&P5] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, G. and N.  van der Poorten (Eds.), 5th Edition, Malayan Nature Society, 2020.
• 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.

Acknowledgment:
I would like to express my gratitude to Timothy Liew, Loh Jian Kai and Zick Soh for sharing information on the host plant and early stages of the White Banded Flat.

Text by Horace Tan, Photos by Loh Mei Yee, Low Jian Kai, Sebastian Ow, Zick Soh, Anthony Wong, Khew SK and Horace Tan.

Butterfly of the Month - July 2025

Butterfly of the Month - July 2025

The White Fourline Blue (Nacaduba angusta kerriana)

A White Fourline Blue perched on a leaf in the forest understorey

We are into the 2nd half of the year 2025, and the summer is in full swing in the northern hemisphere. The weather has been mercilessly hot but yet there have been countries that have been inundated with heavy rains and even suffered fatalities. Over in Singapore, it has been a very hot July with few days of rains in between and we are getting temperature highs in the mid-30's for the month.

A newly eclosed White Fourline Blue perched on its pupal case

It was alarming that even over in our generally peaceful ASEAN region, disputed territorial claims have led to a war level conflict between Thailand and Cambodia. The military on both sides exchanged fire at the border between the two neighbours and escalated to heavy artillery, rocket fire and air strikes on 24 July. There were fatalities, unfortunately affecting civilians where up to 43 people were killed in the crossfire. Ceasefire talks are in progress, although tensions remain high.

It was a generally uneventful month in Singapore, perhaps except for a sinkhole incident that swallowed a car. Fortunately, the lady driver managed to get out of her car and was rescued by some migrant workers from a construction site adjacent to the sinkhole before a burst water mains flooded the hole. The authorities are still investigating the cause of the soil failure and the road remains closed to traffic whilst repairs are in progress.

A mating pair of White Fourline Blue

Over in the US, the topic of tariffs, threats and negotiations are still ongoing with many countries as the deadline of 1 Aug looms. Many trade representatives are pushing negotiations hard to ensure that the proposed tariffs are not imposed on their countries' goods to the US. Despite the volatility and uncertainty, world financial markets appear to be still on a bull run as if these tariffs have been already factored into their projections.

Back to our Butterfly of the Month for July 2025 - a diminutive but extremely rare Lycaenidae called the White Fourline Blue (Nacaduba angusta kerriana). It was re-discovered in late 2008 at Telok Blangah Hills Park when the late ButterflyCircle member Sunny Chir stumbled on a mating pair along the trails and suspected that it was a species that he had not encountered before. Subsequent trips to the location continued and for a few days, the species was flying in the same area.

The White Fourline Blue was on the early authors' checklists but has eluded butterfly watchers until that year. However, besides that very short period, it has been absent again and never reliably seen since. Classified as 'data deficient' in the Singapore Red Data Book 3rd Edition, its mysterious appearance, and disappearance is still unexplainable. Perhaps it is still flying around somewhere in Singapore just waiting to be encountered again someday soon.

Upperside of male White Fourline Blue (top) and female White Fourline Blue (bottom)

The male White FourLine Blue is purplish blue above with a thin black border, which is about 1mm broad towards the apex. The hindwing is unmarked but with a thin submarginal black border. The hindwing cilia is white. The female has broad black border on the forewing and has a light blue ground colour with diffuse greyish markings on both wings.

Beneath, both sexes have greyish ground colour with very broad and diffuse whitish-grey stripes. On each hindwing, there is an orange-crowned tornal spot lightly speckled with bluish-green metallic scaling. i Next to the tornal spot, a pair of filamentous white-tipped tails occur at end of vein 2. Marginal and submarginal spots are black and stand out against the whitish background. The prominent rounded black sub-marginal spot in space 6 of the hindwing serves as an important identification key for this species.

A White Fourline Blue puddling on damp muddy footpath

The White Fourline Blue has an erratic but rather weak flight, and prefers to stay under shade, fluttering amongst thick vegetation along the forest edge. Males tend to stay higher up in the forest canopy, and descend lower to find a mate, or to feed. Males are also observed puddling on damp forest paths in Malaysia. 

A female White Fourline Blue ovipositing on its caterpillar host plant, Entada spiralis

The complete life history has been successfully recorded in Singapore on its caterpillar host plant, Entada spiralis, which it shares with a number of other more common species like the Large Four-Line Blue (Nacaduba pactolus odon), Common Line Blue (Prosotas nora superdates) and the Common Grass Yellow (Eurema hecabe contubernalis).

Text by Khew SK : Photos by Sunny Chir, Khew SK, Low JK and Horace Tan.