Butterfly of the Month - July 2026

Butterfly of the Month - July 2026

The Angled Castor (Ariadne ariadne ariadne)

A female Angled Castor showing its unique underside wing patterns

We are well into the second half of 2026 as the days and weeks fly past so quickly. July 2026 will go down in history as the month of the 2026 FIFA World Cup. Held once every 4 years, the 2026 World Cup is the first time the event was expanded to 48 teams instead of the 32 team format. The tournament was jointly hosted by the United States, Canada and Mexico, the first men’s World Cup staged across three countries. The entire event lasted over 39 days with 104 matches played. Spain won the 2026 FIFA World Cup, beating defending champions Argentina 1–0 after extra time in the final on 19 July 2026.

As the late-night soccer TV binges fade away and the celebrations of the winners end, life goes back to normalcy for the soccer fans. The tenuous peace plan in the Strait of Hormuz is unstable, with neither the US nor Iran willing to stop hostilities in their now 5-month war. Whilst news about the frequent attacks no longer dominates world news, most of the world continues to feel the pinch of rising costs caused by oil price increases and disruptions due to the war.

The US launched a new series of tariffs on trade across the globe, again affecting many countries and causing uncertainty in the world economy. Even tiny Singapore was hit with a new tariff of 12.5% and this time, the tariffs were imposed in the name of forced labour supply chains of manufactured goods. Whilst it was reported that roughly one-third of Singapore's domestic exports are affected by this new tariff, it adds more uncertainty to the companies that export goods to the US.

Back in Singapore, the news that dominated headlines was when Acting Minister-in-charge of Muslim Affairs Muhammad Faishal Ibrahim resigned on 20 July as a minister, MP and PAP member after an investigation into interactions with a woman. Whilst the authorities assessed that neither party had committed a criminal offence, Prime Minister Lawrence Wong said Mr Faishal’s conduct had fallen below the standards expected of a political office-holder. However, the online exchanges between the two still remain confidential, and sparked off speculations and false news on social media, and has people wondering what was it that Mr Faishal wrote that was "inappropriate".

Anyway, back to our seemingly more peaceful butterfly world again. July seems to be a good season for butterflies in Singapore, with a bumper crop of photos of a good variety of species being posted on the local social media platforms. Our feature butterfly for July 2026 is the Angled Castor (Ariadne ariadne ariadne) It was first re-discovered in Oct 2013 at a small forest patch in the Mandai/Ulu Sembawang PCN vicinity. Listed on the early authors' checklists as extant in Singapore, the Angled Castor was not seen until then.

Subsequently, a colony of the species was discovered on Pulau Ubin just a short walk from Butterfly Hill. The Angled Castor, as its name suggests, is dependent on the Castor Oil Plant (Ricinus communis). This plant was found growing in abundance near a storage site on Pulau Ubin. Several individuals were regularly seen at this area, and caterpillars were also spotted on the host plants.

Healthy growth of the Castor Oil Plant on Pulau Ubin.  Unfortunately, the land is now cleared for development.

The seeds of the Caster Oil Plant, from which the toxin, Ricin can be extracted

Commercial castor oil is pressed from the seeds of the Castor Oil Plant and then processed. It is rich in ricinoleic acid, an unusual fatty acid that gives the oil its characteristic thickness and chemical properties. The seeds naturally contain ricin, an extremely toxic protein. Ricin attracts attention because very small quantities can be dangerous if they enter the body. In practice, its notoriety comes mainly from assassinations, intimidation and attempted mail attacks.

On the upperside, the Angled Castor's wings are orangey to reddish brown and traversed by five or six narrow and sinuate black lines. A single black discal line lies just beyond the cell-end on both wings. Superficially, it resembles the more common Chocolate Pansy (Junonia hedonia ida) in flight and sometimes be overlooked due to its resemblance. Both species are skittish and challenging to photograph.

The Angled Castor was first re-discovered at Mandai forest area in 2013.

On the underside, the wings are pale crimson brown and crossed with several irregular bands in darker coloration. Small whitish wing scales are featured dotting the wing surface, in much greater abundance in the female than the male. A prominent white sub-apical spot is featured in the forewing on both under- and uppersides.

The patch of Castor Oil Plant on Pulau Ubin has now been cleared, with a small row cultivated at the foot of Butterfly Hill. Although the Castor Oil Plant is not often a popular plant to be cultivated in parks and gardens, the absence of this host plant may spell the doom for the Angled Castor in Singapore. It is hoped that NParks will continue to cultivate a limited quantity of these plants on Pulau Ubin to sustain a population of this butterfly in Singapore.

Text by Khew SK : Photos by Khew SK, Koh CH, Loh MY, Simon Sng, Michael Soh, Horace Tan and Tea YK

Butterfly of the Month - June 2026

Butterfly of the Month - June 2026

The Hoary Palmer (Unkana ambasa batara)

A female Hoary Palmer extends its exceptionally long proboscis to feed on the flowers of Ixora javanica

Almost half of 2026 is over as we are nearly at the end of the month of June. If you are the type to track your progress of the targets that you set for yourself in 2026, it is past the halfway mark now. Have you achieved what you set out to do at the beginning of the year? Or are you still waiting and procrastinating for the next six months before you get round to completing your personal goals? As the saying goes, time and tide wait for no one, so get cracking!

In global news, one of the biggest geopolitical stories was the de-escalation between the United States and Iran after months of military confrontation. The two sides signed a memorandum outlining a path towards a broader peace agreement, although the situation remained fragile throughout the month. The keyword here is 'fragile' as every day brings new developments and changes to the definition of peace in the Strait of Hormuz.

Unlike the war between Russia and Ukraine, the US-Iran confrontation is very much more in the news, not because it is a more recent development, but more so because the impact of rising fuel prices caused by the blockaded Strait of Hormuz has affected most of the rest of the world as the cost of living issues hit home. Prices of everyday commodities and necessities continue to rise, accelerating inflation and affordability issues that affect everyone.

Back home, The Meteorological Service Singapore announced there was more than an 80% chance of El Niño developing between June and July. Possible impacts include hotter weather, reduced rainfall, increased water demand, elevated haze risk if regional fires in Malaysia and Indonesia occur later in the year. El Nino events typically occur every three to five years, disrupting global weather patterns, and often bringing hotter and drier conditions to Southeast Asia.

Two male Hoary Palmers. Note the bluish tinge in the patches on the hindwings

Thus far, the month of June has been rather wet, with thunderstorms and strong winds occurring many days in the month. However, certain butterfly-watching locations seem to have sprung back to life where more species and numbers of butterflies have been spotted by butterfly watchers over the past two weeks of June. This seasonality in butterflies is something that appears to be easier to track with digital platforms like iNaturalist and social media groups like in FaceBook groups.

We introduce yet another Hesperiidae or Skipper as our Butterfly of the Month for June 2026 - The Hoary Palmer (Unkana ambasa batara). A medium-sized skipper, the Hoary Palmer is classified as "Least Concern" in the Singapore Red Data Book 3rd Edition. Whilst the species cannot be considered common, it has been quite regularly observed by butterfly watchers across a variety of habitats from the forested nature reserves to urban parks and gardens.

Upperside shots of the Hoary Palmer.  Top : Male, Bottom : Female

The Hoary Palmer is dark brown on its upperside, with a series of yellowish-white hyaline spots on the forewing of the male, and bluish-white hyaline spots of the forewing of the female. The hindwing of the male is unmarked whilst that of the female has a white discal patch. The eyes of the Hoary Palmer are dark brown whilst the tip of the apiculus of the antennae is yellow.

The underside of the forewing is partially whitened and almost the whole of the underside of the hindwing is strongly whitened in the female, but more subdued and may appear bluish-white in the male. In pristine individuals, a hint of purple can sometimes be seen in the males when viewed in a sidelight. The abdomen of the male is banded yellow and brown, whilst that of the female is banded white and brown.

The butterfly is swift on the wing and is often photographed feeding on the flowers of Ixora bushes. Interestingly, there appears to be more observations of the Hoary Palmer feeding on the yellow variety of Ixora rather than the red variety. It flies rapidly from flower to flower, extending its exceptionally long proboscis like a fly-fishing fisherman!

The caterpillar of the Hoary Palmer has been successfully bred on two local host plants - Pandanus amarylifolius (Pandanaceae, common name: Pandan), Pandanus tectoris (Pandanaceae, common name: Seashore Pandan, Screw Pipe). Interestingly, despite the strong smell of the local Pandan plant (which is sometimes used to ward off ants and cockroaches), the caterpillar and the adult butterfly of the Hoary Palmer does not seem to be affected by it.

Text by Khew SK : Photos by David Chan, Khew SK. Michael Khor, Koh CH, Richard Ong, Zick Soh, Horace Tan, Anthony Wong, Mark Wong and Angela Yeo.

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.