Butterfly of the Month - October 2025

Butterfly of the Month - October 2025

The Narrow Spark (Sinthusa nasaka amba)

A Narrow Spark feeding on the flowers of the Bandicoot Berry (Leea indica)

We are well into the 4th Quarter of 2025 and the tenth month of the year will soon be history. Speaking of history, for the first time, Singapore's population reached a historical high of 6.11M residents on this little island nation. Driven by foreign workers (especially in construction, marine shipyard, domestic sectors), that means that there is 120m2 of land area per person in Singapore - only Monaco (38m2 per person) and Macau (50m2 per person) are denser globally.

In global politics, Japan has made another historical first - Sanae Takaichi was elected as Prime Minister of Japan and the first woman ever to serve as Prime Minister of Japan in the country’s modern history. Since Japan’s first post-war prime minister in 1947 (Shigeru Yoshida), all 32 prime ministers before Sanae Takaichi have been men.

On 20 Oct 2025, the Hindu community in Singapore celebrated the Festival of Lights or Diwali (also known as Deepavali. Deepavali in Singapore is both a religious festival and a national celebration of cultural diversity — a time when the whole city, not just the Indian community, joins in the joy and light. It is one of the most vibrant and widely celebrated cultural festivals — recognized as a public holiday and an important part of the nation’s multicultural calendar.

A Narrow Spark feeding on the flowers of the Buas-Buas shrub (Premna serratifolia)

Our feature butterfly for the month of October 2025 is the diminutive Narrow Spark (Sinthusa nasaka amba) a forest-dependent Lycaenidae that was first recorded in Singapore some time in 1995. Early references did not record this butterfly as extant in Singapore and it is still considered an "exotic" even after 30 years!  Butterfly observers would, by now, take this species as a Permanent Resident as it has been quite regularly observed in the forested nature reserves.

A newly eclosed female Narrow Spark perched on a twig

The Narrow Spark is sometimes mistaken for the more common, and larger, Common Tit (Hypolycaena erylus teatus) as its general appearance is quite similar.  The Narrow Spark, however, is only about half the size of the Common Tit, and has distinguishing differences when viewed more closely. Firstly, the Narrow Spark has only two white-tipped filamentous tails on the hindwing, whilst the Common Tit features four.

A female Narrow Spark shows off its uppersides whilst sunbathing

Above, the male Narrow Spark is a luscious ultramarine blue with a dark brown costal border. The female is dark brownish-black with a white tornal area bearing black spots on the hindwing. On the underside, there is an ochreous median stripe that is prominently continuous across both wings, but broken on the hindwing. The apical area of the forewing is shaded orange.

On the hindwing, there is a large prominent black spot and another on the lobe at the tornal area. The tornal area is sparsely dusted with metallic green scales and features a filamentous white-tipped tail at vein 2 of the hindwing. The eyes are an opaque jet black whilst the antennae are black-and-white banded with an orange tip at the clubbed end. The legs are also black-and-white banded.

The Narrow Spark has been successfully bred on Eurya acuminata in Singapore. The caterpillar host plant is common in the forested nature reserves and despite its status as "exotic" in the Singapore checklist, it may be likely that this tiny butterfly may have been missed by the early authors and has existed in Singapore all this time.

Text by Khew SK : Photso by Choy Chan Wah, David Ho, Khew SK, Koh CH, Lee Yue Teng, Loh MY, Michael Soh, Horace Tan and Mark Wong 

Life History of the Malay Red Flash

Life History of the Malay Red Flash (Rapala damona)

Butterfly Biodata:
Genus: Rapala Moore, 1881
Species: Species: damona Swinhoe, 1890
Wingspan of Adult Butterfly: 25-28mm
Caterpillar Local Host Plants: Cordia cylindrostachya (Boraginaceae, common names: String Bush, Scorpion Weed, Black Sage), Melastoma malabathricum (Melastomataceae, Singapore Rhododendron) .

A female Malay Red Flash perching on leaf at a forest edge.

Another female Malay Red Flash on a leaf perch.

A female Malay Red Flash taking nectar on a String Bush inflorescence.

Physical Description of Adult Butterfly:
On the upperside, the female is entirely brown whereas the male is deep red with broad black border on the forewing. As with other Rapala spp., the male has an oval-shaped brand in space 7 on the hindwing. On the underside, both sexes are ochreous brown. The markings are typical for Rapala spp, with cell-end bars on both wings, and narrow brown postdiscal bands. In the forewing, the postdiscal band is curved-in at the upper quarter. The hindwing carries a white-tipped filamentous tail at the end of vein 2 with a tornal lobe between veins 1a and 1b. In addition, there is a black tornal spot, a bluish green patch in space 1b (about 80-100% filled), an orange-crowned (either pale orange, yellow or obscure), black sub-marginal spot in space 2, and black post-discal striae in spaces 1b and 2.

A female Malay Red Flash found in a grassy patch.

Upperside view of a male Malay Red Flash.

A male Malay Red Flash found in a park.

Field Observations:
The Malay Red Flash is moderately rare in Singapore. It is mainly found at the fringe of the nature reserves and in some urban parks. The adults are fast flyers and take rapid flights among foliage at forest edges and around their host plants. Adults also visit flowers for their nectary intakes.

A male Malay Red Flash taking nectar from a String Bush inflorescence.

A male Malay Red Flash on a leaf perch.

A male Malay Red Flash taking nectar from a String Bush inflorescence.

Early Stages:
The Malay Red Flash is polyphagous as its early stages feed on host plants from different families. Locally two plants, Cordia cylindrostachya (String Bush) and Melastoma malabathricum (Singapore Rhododendron), have so far been identified as the larval hosts. The caterpillars of the Malay Red Flash feed on flowers and flower buds of the host plants. In the wild, the caterpillars are typically found in the company of small black ants.

Local host plant #1: Cordia cylindrostachya (String Bush).

Local host plant #2: Melastoma malabathricum (Singapore Rhododendron).

Eggs are laid singly on a leaf, on the peduncle and among flower buds on a developing inflorescence. Each egg is about 0.6-0.7mm in diameter, greenish in colour when freshly laid. It is bun-shaped with a depressed micropylar at the pole and a surface reticulated with very fine ridges.

A female Malay Red Flash ovipositing on an inflorescence of the String Bush.

A tattered female Malay Red Flash attempting to oviposit on an inflorescence of the String Bush.

Two close-up views of an egg of the Malay Red Flash.

Three views showing the development of an egg the Malay Red Flash, with the rightmost showing the empty egg shell.

It takes about 3 days for the egg to hatch. The newly hatched is pale yellowish brown with moderately long dorsal and lateral setae. Its body has a length of about 1mm. Pale reddish brown patches can be seen on the dorsum of the metathorax, 1st, 6th-8th abdominal segments. It also has a black prothoracic shield and a black head. After about 2.5 days of growth in the first instar, and reaching a length of about 2mm, the caterpillar moults to the next instar.

Two views of a 1st instar caterpillar of the Malay Red Flash on a flower bud of the String Bush, a few hours after hatching, length: 1mm.

Two views of a 1st instar caterpillar of the Malay Red Flash among the flower buds of the String Bush, length: 1.9mm.

A 1st instar caterpillar of the Malay Red Flash feeding on a flower bud of the Singapore Rhododendron.

Two views of a late 1st instar caterpillar of the Malay Red Flash, dormant prior to its moult.

The 2nd instar caterpillar is pale yellowish brown in base color and has dark reddish brown patches on the dorsum of the metathorax (the posterior half), as well as in the 1st, 6th-8th abdominal segments. There are short black setae emanating from rows of conical projections occurring dorsally and laterally. The dorsal conical projections are larger and more whitish compared to those occur on later body segments. The 2nd instar caterpillar reaches a length of about 3mm, and after about 2.5 days in this stage, it moults again.

Two views of a 2nd instar caterpillar, length: 2.4mm.

Two views of a 2nd instar caterpillar of the Malay Red Flash, length:3mm.

A 2nd instar caterpillar of the Malay Red Flash feeding on a flower bud of the Singapore Rhododendron.

Two views of a late 2nd instar caterpillar of the Malay Red Flash, dormant prior to its moult.

The 3rd instar caterpillar resembles the 2nd instar caterpillar closely, but top of the conical projections of 2nd-6th abdominal segments more whitish, giving rise to the appearance of two parallel whitish bands on the dorsum. Individual caterpillars raised on flowers of the Singapore Rhododendron typically have a strong pink to reddish undertone compared to those raised on String Bush. On the 7th abdominal segment, the dorsal nectary organ is now more readily observed. The 3rd instar takes about 2.5 days to complete with the body length reaching about 5mm before the next moult.

Two views of an early 3rd instar caterpillar of the Malay Red Flash, length: 3.5mm.

Two views of a 3rd instar caterpillar of the Malay Red Flash, length: 4mm.

A 3rd instar caterpillar of the Malay Red Flash moving on a flower part of the Singapore Rhododendron.

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

Two views of a late 3rd instar caterpillar of the Malay Red Flash, dormant prior to its moult on a leaf of the Singapore Rhododendron, length: 5mm.

The 4th instar caterpillar again resembles closely the 3rd instar caterpillar. One discernible difference is in the reddish brown patches on the dorsum of the metathorax and 1st abdominal segments. These patches are now somewhat disjoint at the mid-dorsal line. Tentacular organs on the 8th abdominal segment can now be easily observed being everted from time to time. The 4th instar takes about 3 days to complete with the body length reaching up to 10mm.

Two views of an early 4th instar caterpillar, length:6mm.

Two views of a 4th instar caterpillar, length: 7.5mm.

A 4th instar caterpillar of the Malay Red Flash feeding on a flower part of the Singapore Rhododendron.

A 4th instar caterpillar of the Malay Red Flash with ants in attendance.

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

The 5th instar caterpillar has similar markings as in the 4th instar but with greater separation of the left and right halves of the dorsal reddish brown patches on the metathorax and 1st abdominal segment. The two parallel whitish bands on the 2nd-6th abdominal segments are replaced with disjoint and oblique whitish patches. It is not uncommon to see numerous ants attending to a 5th instar caterpillar in field observations.

Two views of an early 5th instar caterpillar of the Malay Red Flash, newly moulted.

An early 5th instar caterpillar of the Malay Red Flash feeding on an inflorescence of the String Bush.

Two view of a 5th instar caterpillar of the Malay Red Flash feeding on the Singapore Rhododendron, length: 17mm.

Two view of a 5th instar caterpillar of the Malay Red Flash, length: 19mm.

A 5th instar caterpillar of the Malay Red Flash being attended by ants on an inflorescence of the String Bush.

After about 4-5 days of feeding and reaching a length of about 19-20mm, the caterpillar stops food intake and wanders around for a pupation site. During this time, its body gradually shortened and body color darkens. Typically the caterpillar chooses a concealed space in a leaf litter for its pupation site.

Two views of a late 5th instar caterpillar of the Malay Red Flash with body color darkened.

Two views of another late 5th instar caterpillar of the Malay Red Flash with body color darkened.

The pre-pupatory caterpillar prepares for pupation by spinning a silk girdle and a silk pad to which it attaches itself via anal claspers. After about 1 day as a pre-pupa, pupation takes place. The pupa has a shape typical of most lycaenid species with a length of 10-12mm. It is pale reddish to yellowish brown in base colour, and its surface bears numerous small dark speckles.

Two views of a pre-pupa of the Malay Red Flash.

Two views of a pupa of the Malay Red Flash.

Eight to nine days later, the pupa darkens, first in the wing pad and thorax, then progressively in the abdomen. The next day, the pupal stage comes to an end with the emergence of the adult butterfly. Pupal period: 9-10 days.

Two views of a mature female pupa of the Malay Red Flash.

A newly eclosed female Malay Red Flash.

Another newly eclosed female Malay Red Flash 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.
• Butterflies of Thailand, Pisuth Ek-Amnuay, 2nd Edition, 2012.

Acknowledgment:
I would like to express my gratitude to Mr Foo Jit Leang and Mr Hanpeng Lim for sharing information on the host plant and early stages of the Malay Red Flash.

Text by Horace Tan, Photos by Hanpeng Lim, Loh Mei Yee, Low Jian Kai, Khew SK, Sebastian Ow, Zick Soh, Jonathan Soong and Horace Tan.