Life History of the Transparent Sixline Blue

Life History of the Transparent Sixline Blue (Nacaduba kurava nemana)

Butterfly Biodata:
Genus: Nacaduba Moore, 1881
Species: kurava Moore, 1858
Subspecies: nemana Fruhstorfer, 1916
Wingspan of Adult Butterfly: 26-30mm
Caterpillar Local Host Plant: Ardisia elliptica (Myrsinaceae, common name: Seashore Ardisia).

A male Transparent Sixline Blue perching on a leaf.

A male Transparent Sixline Blue.

A male Transparent Sixline Blue with identification keys indicated.

Physical Description of Adult Butterfly:

Above, the male is violet blue with a thread-thin border (with underside markings visible due to transparency); the female is pale shining blue becoming whitish beyond the forewing cell. Underneath, both sexes are greyish brown with three bands (post-discal, discal and basal) each composed of a double series of whitish striae inwardly lined with dark striae. Forewing postdiscal band is usually straight. On each hindwing, there is an orange-crowned tornal spot in space 2 lightly speckled with bluish-green metallic scales. Next to the tornal spot, a pair of filamentous white-tipped tails occurs at end of vein 2. Forewing submarginal spots are mostly rounded or with scalloped inner margins. In the hindwing, the postdiscal band is usually close to the submarginal band, and submarginal spot 6 is large and often quadrate. The female has more rounded forewing termen than the male.

A female Transparent Sixline Blue resting on a stem of Dendrolobium umbellatum. Note the rounded forewing termen.

A male Transparent Sixline Blue resting on a flower of Coat Buttons.

A female Transparent Sixline Blue perching on a peeled bark.

Field Observations of Butterfly Behaviour:

The Transparent Sixline Blue is moderately common in Singapore. The adults have been seen flying in the vicinity of the host plant, visiting flowering plants, puddling on wet grounds and performing oviposition rituals at developing inflorescence of the host plant.

A male Transparent Sixline Blue resting on a stem of Dendrolobium umbellatum.

A male Transparent Sixline Blue checking out some Lantana flowers.

A male Transparent Sixline Blue perching on a leaf in a nature park.

Early Stages:

The Transparent Sixline Blue is polyphagous. However, for Singapore, only one local host plant, Ardisia elliptica, has thus far been recorded. Caterpillars of the Transparent Sixline Blue mainly feed on leaves and flower buds of the host plant. As in the case for most lycaenid species, the caterpillars of the Transparent Sixline Blue are tended by ants.

Local host plant: Ardisia elliptica.

A mother Transparent Sixline Blue ovipositing on a young leaf of Ardisia elliptica.

Eggs are laid singly on a leaf or stem of the host plant. Each egg is whitish with a green undertone. It has a thick discoid shape, and features a depressed micropylar on top. The egg surface is finely reticulated, slightly raised at the intersections of cris-crossing ridges. Th egg has a diameter of about 0.6mm.

A newly laid egg of the Transparent Sixline Blue on a stem of Ardisia elliptica.

Eggs of the Transparent Sixline Blue laid on leaf surface.

It takes about 2.5-3 days for the egg to hatch. The young caterpillar consumes part of the egg shell to emerge. With a length of about 1mm, it has a pale yellowish body with long setae (hairs) dorsally and sub-spiracularly. The head is black in colour in this instar. The body color changes gradually to a brighter shade of yellow as growth progresses. The first instar lasts for 2-2.5 days and the body length reaches about 2mm before the moult to the 2nd instar.

Two views of a newly hatched caterpillar of the Transparent Sixline Blue, length: 1mm.

Two views of a 1st instar caterpillar of the Transparent Sixline Blue, length: 2mm.

Two views of a late 1st instar caterpillar of the Transparent Sixline Blue, dormant prior to its moult.

In the second instar, dorsal setae are much shortened proportionately compared to those in the first instar. Moreover, there are numerous short setae present all over the body surface. The body color is mainly pale yellow while the head is pale reddish brown. The 2nd instar lasts for 2-2.5 days and the caterpillar grows to a length of about 4mm.

A freshly moulted 2nd instar caterpillar of the Transparent Sixline Blue.

Two views of a 2nd instar caterpillar of the Transparent Sixline Blue, length: 2.5mm.

Two views of a 2nd instar caterpillar of the Transparent Sixline Blue, length: 3.9mm.

A late 2nd instar caterpillar of the Transparent Sixline Blue, dormant prior to its moult.

The 3rd instar caterpillar is pale yellowish with a green undertone. The dorsal nectary organ and tentacular organs are now easily discernible. After about 3 days in this instar with the body length reaching about 7-7.5mm, the next moult brings the caterpillar to its final instar.

A freshly moulted 3rd instar caterpillar of the Transparent Sixline Blue.

Two views of a 3rd instar caterpillar of the Transparent Sixline Blue, length: 5.1mm.

Two views of a 3rd instar caterpillar of the Transparent Sixline Blue, length: 6.4mm.

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

Two caterpillars of the Transparent Sixline Blue observed with an attending ant in a local park.

The 4th instar caterpillar has the same pale yellowish ground color as in the 3rd instar, but some individuals also possess a reddish/pinkish dorsal band and/or small reddish dorso-lateral marks. As in the 3rd instar, the dorsal nectary organ and tentacular organs are prominent on the posterior segments. Tentacular organs are readily everted when the caterpillar senses a threat (such as from a competing caterpillar) or when attending ants are present.

A freshly moulted 4th instar caterpillar of the Transparent Sixline Blue.

Two views of a 4th instar caterpillar of the Transparent Sixline Blue, length: 10.3mm.

Two views of a 4th instar caterpillar of the Transparent Sixline Blue, with pinkish dorsal band, length: 14.5mm.

A 4th instar caterpillar of the Transparent Sixline Blue, feeding on flower buds of Ardisia elliptica in a local park.

Another 4th instar caterpillar of the Transparent Sixline Blue, feeding on Ardisia elliptica in a local park.

The 4th instar lasts for 4-5 days and the body grows up to a length of about 14-14.5mm. On the last day of this instar, the caterpillar ceases food intake and its body shrinks in length and decolorises to a dull shade of yellowish to pinky brown. The fully grown caterpillar finally comes to rest on a spot among leaves where it readies the site for pupation by spinning a silk pad and a silk girdle to secure itself.

A 4th instar caterpillar of the Transparent Sixline Blue, late in this stage, with color change taken place.

Two views of a girdled-down pre-pupa of the Transparent Sixline Blue.

About 1 day later, pupation takes place. The pupa has the typical lycaenid form, and is 9-10.2mm in length. It is mostly pale yellowish brown and speckled with black spots of various sizes and shapes.

Two views of a pupa of the Transparent Sixline Blue

Four to five days later, the pupa becomes darkened in color signaling the imminent emergence of the adult. The markings on the forewing upperside becomes increasing obvious through the pupal skin. The next day the adult butterfly emerges from the mature pupa. Pupal period: 5 to 6 days.

Two views of a mature male pupa of the Transparent Sixline Blue, showing extensive purplish blue coloration in the wing pad.

Two views of a mature female pupa of the Transparent Sixline Blue, showing much less extensive bluish coloration in the wing pad.

A newly eclosed female Transparent Sixline Blue resting near 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.
• A Field Guide to the Butterflies of Singapore, Khew S.K., Ink On Paper Communications, 2nd Edition, 2015.
• Butterflies of Thailand, Pisuth Ek-Amnuay, 2nd Edition, 2012.

Text by Horace Tan, Photos by Khew SK, Koh Cher Hern, Low Jian-Kai and Horace Tan.

Butterfly of the Month - May 2026

Butterfly of the Month - May 2026

The Common Redeye (Matapa aria)

A Common Redeye perched on top of a leaf in the shaded forest understorey

May 2026 is almost over. Five months have passed. The tumultuous world continues to be more fragmented, contested, and unpredictable. The highlight of the month of May was the US President's official visit to China. This was President Trump's 2nd visit to China after a nine-year interval. The visit dominated news portals for a week as speculations of what news, good or bad, will come out of the visit between the Presidents of the two most powerful nations in the world today.

As can be expected, the conclusions of the outcome of the visit were quite different on both sides, but the US outlined several agreements made. The White House reported that "Both leaders agreed Iran cannot have a nuclear weapon, called to reopen the Strait of Hormuz, and agreed that no country or organization can be allowed to charge tolls." Whilst this sounded like good news, the actual events on the ground at the Strait of Hormuz indicate that there is no certainty that the US will end the war just yet.

On the issue of Taiwan, President Xi remained resolute in his stance, and reserved his sharpest language for Taiwan, calling it “the most important issue in U.S.-China relations.” The stakes, he said, could not be higher: “Handle it well, the relationship holds; handle it badly, the two countries risk collision or conflict.” The US President avoided a direct reply, indicating instead that the "US policy on Taiwan remained unchanged."

Just two weeks after President Trump's visit to China, the 23rd Shangrila Dialogue - the 23rd edition of Asia's leading annual defence summit was held in Singapore. In his address, the US Secretary of War, Peter Hegseth said there is “rightful alarm” over China’s rapid military expansion and increasing military activity across the region. Hegseth called on U.S. allies and partners in Asia to increase defence spending, saying Washington expects partners to contribute more to their own security. One can only wonder if world peace is really a priority?  

Back to our more peaceful butterfly world and we feature our Butterfly of the Month for May 2026 - a small skipper called the Common Redeye (Matapa aria). A species of the Hesperiidae family, the Common Redeye is only known up to species level, implying that there are no geographically different subspecies across the world where it occurs.

Upperside of a newly-eclosed Common male Common Redeye

The Common Redeye is buff brown above and unmarked with the hindwing cilia, particularly in pristine individuals, a yellowish-white. Males have two obscure bowed brands on the upperside of the forewings. The underside is an ochreous brown, sometimes appearing almost a deep orange and unmarked. The abdomen is unicolourus with the wings and also without any bands or distinguishing features.

A macro closeup of the red eye of the Common Redeye

The most obvious feature of this species is its large bright red eyes that often stand out prominently in any photograph of it. The antennae tips are dark brown including the apiculus. The legs are plain ochreous brown throughout.

The Common Redeye is uncommon but not considered rare in Singapore. However, at times, the caterpillars can be found quite regularly on its host plants - various species of bamboo. This suggests that the species may be more common than believed - just that the adult butterfly may be shy and hard to spot in the field. The species is found mainly in urban parks and gardens where bamboos are cultivated, as well as in the forested nature reserves and our offshore islands.

The adult butterfly is more active at certain hours of the day - usually at dawn or dusk. At other times of the day, it may be spotted resting on the tops of leaves in the shaded forest understorey. It is a fast flyer and rests with its wings folded upright. Unlike many skippers, it is rarely spotted with opened wings in the usual skipper fashion. It has been successfully bred on Bambusa heterostachya (Malay Dwarf Bamboo), Bambusa multiplex (Hedge Bamboo, Chinese Dwarf Bamboo) and other Bambusa spp., Dendrocalamus spp.

Text by Khew SK : Photos by David Chan, David Ho, Khew SK, Koh CH, Lim KH, Low JK, Bobby Mun, Richard Ong, Horace Tan, Soh KY, Bene Tay, Art Toh and Yam TW.