26 March 2008

Three Posies

Featuring the Common Posy, Dark Posy and Pygmy Posy

One of the definitions of the word Posy is a bouquet. Indeed, the three species of Posy found here in Singapore resemble colourful flowers with attractive black markings. Each species is endowed with three pairs of tails on the hindwings with the tail at vein 2 being the longest of the three.

The Posies belong to the genus Drupadia, of which three species are known to exist in Singapore. All three are forest species and are usually encountered in the nature reserves in the shaded understorey. At times they are found sunbathing with wings opened flat, displaying their blue or purple uppersides. They have a habit of fluttering with a skipping flight, and in some individuals, returning to the same favourite perch time and again. Males generally have a stronger flight than females.

The Common Posy (Drupadia ravindra moorei)

The most frequently encountered species is the Common Posy (Drupadia ravindra moorei). In the male, the forewing is dark brown and the hindwing a very attractive azure blue. The female is mainly brown, with a faint orange discal patch in some individuals. The underside is orange on the forewing with orange and black markings, and mainly white on the hindwing, with black solid bands and spots. Along the tornal edge are iridescent blue scales and the black-centred white tails emerge from veins 1b, 2 and 3, with the tail at vein 2 being the longest.

Upperside of a male Common Posy

Upperside of a female Common Posy

The Dark Posy (Drupadia theda thesmia)

The next species, the Dark Posy (Drupadia theda thesmia) is less often seen but occasionally several are seen together, frolicking at tree-top level in the late hours of the afternoon basking on the tops of leaves when the sun shines through the forest canopy. The male is dark purple above with an orange discal patch on the forewing. This form, f-minara is the typical male form found in Singapore. The female is brown with a bluish grey tornal patch on the hindwing which has a few black submarginal spots.

Upperside of a male Dark Posy

Upperside of a female Dark Posy

On the underside, the forewing is dark orange marked with darker transverse stripes, whilst the hindwing is white with black spots and lines. This species can be separated from the lookalike Common Posy in that the space between the two black stripes forming the cell-end bar on the hindwing beneath is white, and not solid black as in the Common Posy.

The Pygmy Posy (Drupadia rufotaenia rufotaenia)

The final and rarest of the three Posy species in Singapore is the Pygmy Posy (Drupadia rufotaenia rufotaenia). This species, which suggest a small female of the Common Posy, which it resembles. The Pygmy Posy has a wingspan of 20mm, which is about half the size of its other two cousins. In Singapore, it is often seen feeding on the sugary sap of the young shoots of the forest bush, Leea indica, where it stays still for long periods of time unless disturbed.

It can be reliably separated from the other two Posies in that the narrow submarginal orange band on the hindwing beneath is continuous from 1a and extends to vein 3.

Text by Khew SK ; Photos by Khew SK, Sunny Chir, Horace Tan, Federick Ho.

11 March 2008

Butterfly of the Month - March 2008

The Fivebar Swordtail (Pathysa antiphates itamputi)

During certain times of the year, the Fivebar Swordtail can be observed puddling at damp spots along streams and footpaths in the nature reserves of Singapore. It is essentially a forest butterfly and is rarely seen in urban parks and gardens, preferring the sanctuary of the forested reserves .

In Singapore, after a prolonged rainy season towards the end of 2007, the species was rarely seen during the last few months of the year. As the weather turned hotter and drier after the Lunar New Year, a number of Fivebar Swordtails were seen puddling in the nature reserves. During the drier weeks towards the end of February and March 2008, the species became relatively more common and was spotted in various areas around the nature reserves. The species is a favourite amongst butterfly photographers, where it is easily photographed when puddling at damp sandy spots.

When in flight, it can often be mistaken as a Pierid species, as the long tails are not visble when it is encountered flying rapidly along the edges of the forested areas on sunny days. It is swift and erratic on the wing, and when in full flight, seldom stops to rest.

Males of the Fivebar Swordtail are frequently encountered puddling at moist spots. At times, more than one individual is seen, and also in the company of other Papilionidae like the Common Bluebottle (Graphium sarpedon luctatius) and the Blue Jay (Graphium evemon eventus).

The Fivebar Swordtail has the characteristic long, slender and tapering tail at vein 4 of the hindwing, which is consistent in all the species of the genus Pathysa. The Fivebar Swordtail is the only representative of the genus in Singapore. The long sword-like tails are probably the source of inspiration for the common name of the species.

The species is creamy white above with a series of black transverse stripes in the costal area of the forewing and in which the basal and distal interspaces are filled with green. On the underside, the basal half of the hindwing is green, with black stripes and spots, with a distal half of the hindwing orange yellow.

The long tapering white-tipped tails measure about 4-5cm and project elegantly behind the butterfly as it stops to rest or feed. The body of the butterfly is white, with a lateral black stripe along the thorax, and breaking up into dashes along the abdomen. The eyes are an opaque jet black.

The Malaysian & Singaporean subspecies of the Fivebar Swordtail has the distinction of being one of the few butterflies in the region to bear a local name itamputi from the Malay words hitam meaning black, and putih meaning white.

Text by Khew SK : Photos by Khew SK, Wong CM, James Chia, Horace Tan, Simon Sng and Sunny Chir

09 March 2008

Life History of the Chestnut Angle

Life History of the Chestnut Angle (Odontoptilum angulatum angulatum)

Butterfly Biodata:
Genus: Odontoptilum de Niceville, 1890
Species: angulatum C. Felder, 1862
Subspecies: angulatum C.Felder, 1862
Wingspan of Adult Butterfly: 40mm
Caterpillar Host Plants: Commersonia bartramia, Talipariti tiliaceum (Sea Hibiscus)

Physical Description of Adult Butterfly:
The forewing termen is sinuous, and the hindwing prominently stepped at vein 7. The upperside is chestnut-brown with a complex, cryptic pattern, and has a crescentic hyaline spot in space 2, and a smaller spot above it near the base of space 3. Hindwing has elongated tornal cilia. The male possesses a tuft of white hairs on the fore coxae, and the female has a thick anal tuft on the abdomen.

Field Observations of Butterfly Behaviour: This species is rather rare in Singapore. The adults are usually found near its larval food plants, or when feeding along a muddy track or on bird droppings. In Singapore, it may be found in an urban bushland where Commersonia bartramia grows, or about trees of Hibiscus tiliacus in coastal wetland. They frequently fly rapidly in bright sunshine in open spaces within forests or bushland, and visit flowers for nectar. Other sighting locations include various parts of the Central Catchment Area. Early Stages:

Host plant : Commersonia bartramia

The eggs are laid singly on the leaf upperside. Each egg is white and almost spherical with a flattened base and vertical ridges. The diameter is about 0.9mm. After an egg is laid, the mother butterfly rubs the tip of her abdomen over it. In so doing, pale brown abdominal hairs are glued to the chorion, effectively concealing the egg.

Egg covered in hairs (left), with hairs lost (right)

Mature egg (left), empty egg shell (right)
It takes 7 days for the collected egg to hatch. The young caterpillar eats just enough of the shell to emerge, and has a length of about 2mm. It has the typical cylindrical shape for skipper caterpillars, and there are short setae arising from regular rows of tubercles. The head is bilobed and hairy. The length of these fine "facial" hairs increases with instars.

1st instar caterpillar, length: 2.5mm

Soon after, the young caterpillar constructs its first leaf shelter by making short, curved cuts at the edge of the leaf and turns a small flap. It rests within the flap and ventures out to eat on nearby leaf surface.

The 1st leaf shelter for the 1st instar caterpillar
In later instars, the Chestnut Angle caterpillars make sinuous cuts which avoid the main veins so that the leaf flap remains green. They eat through the leaf at various points between leaf veins on this flap and this results in numerous holes appearing on the leaf shelter. It is interesting to note that Chestnut Angle caterpillars ballistically eject their individual faecal pellets (frass) at great speeds.

2nd instar caterpillar, early in this stage, length: 4mm

After 4 days in 1st instar and reaching a length of about 3.5mm, the caterpillar moults to the next instar. The 2nd instar (and in later instar) caterpillar has its body covered with short hairs arising from numerous low tubercles.

2nd instar caterpillar, late in this stage, length: 5mm

The 2nd instar caterpillar reaches a length of about 5.5mm, and after 6 days in this stage, it moults again. The 3rd instar takes 10 days to complete with the length reaching 12-13mm. During this period, the body color is initially yellow with a green undertone, but as the caterpillar develops, the color changes gradually to creamy white.

3rd instar caterpillar, early in this stage, length: 6mm

3rd instar caterpillar, late in this stage, length: 10mm

The 4th instar takes about 7 days to complete with body length reaching 19-20mm. The facial hairs are now visibly long and prominent.

4th instar caterpillar, early in this stage, length: 14mm

A leaf shelter for a 4th instar caterpillar in the field
The final and 5th instar cat has rather long and dense hairs on its head, giving it a very bushy appearance. This stage takes about 10 days to complete with body length reaching 30mm.

5th instar caterpillar, late in this stage, length: 27mm

At the end of 5th instar, the body of the caterpillar shrinks in length. Soon it becomes dormant in its leaf shelter and enters the preparatory pupa phase which lasts for one day.

Preparatory pupa of Chestnut Angle

Pupation takes place within the leaf shelter. The pupa secures itself with its cremaster attached to a short transverse band, and with vertcal and oblique threads connecting the transverse band and dorsal point of the girdle to the shelter wall. The pupa has a short thorax, a rather long abdomen, a short rostrum and low projections behind the prothoracic spiracles. There is also a pair of small but distinct orange projections on the anterior part of the mesothorax. Its body appearance is mostly white with a light green undertone, and against this background there are black spots arranged in neat symmetrical layout. Length of pupae: 17-19mm.

Fresh pupa of Chestnut Angle

After 7 days, the pupa becomes darkened in color signaling the imminent emergence of the adult. The next day the adult butterfly emerges from the mature pupa.

Mature pupa of Chestnut Angle

A newly eclosed Chestnut Angle

A newly eclosed Chestnut Angle resting on the inner side of a plastic container, showing its underside

  • The Butterflies of the Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society.
  • The Butterflies of Hong Kong, M. Bascombe, G. Johnston, F. Bascombe, Princeton University Press 1999
Text and Photos by Horace Tan

06 March 2008

Voyage of the Tawny Coster

The Voyage of the Tawny Coster (Acraea terpsicore)

Some time back in 2006, a member of ButterflyCircle, Rey Aguila, photographed a mating pair of orange coloured butterflies which he thought were moths. Upon seeing the posted shot, we immediately knew that the Tawny Coster had finally completed its long voyage to Singapore, which started in India and Sri Lanka - a journey which probably took over three decades to complete.

ButterflyCircle members went to the open patch of wasteland to investigate where the pair was first sighted, and found to our pleasant surprise, a colony of the Tawny Costers at the site. Fluttering effortlessly in the breezy area were a good number of males and females of this new addition to the Singapore checklist. They had finally arrived in Singapore!

The Tawny Coster is known to be common in India and Sri Lanka, where it can be found both in forest clearings and open country. Though mainly seen at low elevations, it has been recorded at heights of up to 7,000 ft in South India and sometimes in the north.

Tracing the route of this new species for the region, we found documentary evidence of the appearance of this species in Thailand in the early 80's. How long it had taken to move over land from India and Sri Lanka past Bangladesh, Myanmar and finally to Thailand, is anybody's guess. But it was already a resident species in Thailand by the early 80's.

Sporadic sightings were recorded in South Thailand and the northern part of West Malaysia, and a confirmed record specimen was collected by Arshad at the edge of the Batu Pahat forest reserve in Perlis in 1992. Another sighting was made by Wong Tet Seng in early 1993 near Tanjung Rhu on Pulau Langkawi and subsequently on open land in Bukit Mertajam in the northern state of Penang in April 1993.

It was also recorded on Penang island in that year. Sightings of the species in the remaining years of the 90's were scattered and undocumented. It appeared in 2002 in Petaling Jaya, and was photographed by a butterfly enthusiast. A further sighting was recorded in 2003 in Negri Sembilan.

No further documented records of the sighting of the butterfly were found until 2006 when it appeared at an open wasteland in the north-eastern part of Singapore island. It spread across the island and has become a rather common species all over Singapore, including the offshore island of Pulau Ubin.

A further bonus sighting of the butterfly by veteran nature guide, Subaraj Rajathurai, was made on the Indonesian island of Batam, immediately after it was observed in Singapore.

The Tawny Coster (Acraea terpsicore)

The Tawny Coster belongs to the family Nymphalidae ; Subfamily Heliconiinae. The butterflies of this subfamily are characterised by a perfectly flat hindwing and by having the cells of both wings closed by tubular veins. Their behaviour is sluggish, and, like the Danainae, they have a leathery body and are tenacious of life. They frequently exhibit Mullerian mimicry and serve as models for Batesian mimics from other families. The subfamily is strongly represented in the Ethiopian region, less so in the Neotropical Region, and is weakly represented in the Oriental and Australiasian Regions.

The egg resembles that of Danaini being much higher than wide and bearing rather ill-defined vertical ribs. The eggs are laid in clusters and the gregarious larvae are cylindrical and bear branched spines, termed scoli, on each segment. The host plants are commonly species of Passifloraceae.

The female Tawny Coster typically oviposits a large clutch of eggs numbering anywhere from 20 to 50 eggs in one sitting. The eggs are carefully arranged on the undersides of a leaf of the host plant. In Singapore, the species has adapted itself to the host plant Passiflora foetida. This host plant, a common "weed" growing in wasteland and cleared open areas, is a fast-growing vine.

The relatively plentiful availability of the host plant could be one of the reasons for the rapid spread of the Tawny Coster across Singapore. Furthermore, as each clutch of eggs hatch, the large numbers of caterpillars would make the species more likely to succeed in colonising areas where the host plants are abundant. As the Tawny Coster is distasteful to predators like birds, this also gives it a better chance of survival.

The upperside of the Tawny Coster is a deep orange in the male and a lighter orange-yellow in the female. There is a transverse black spot in cell, and another irregular, oblique and broader at the disco-cellulars. The upper four spots of the discal series inclined obliquely outwards, the lower two obliquely inwards The hindwing possesses a basal series of four or five black spots with a similar spot beyond in middle of cell and a subcostal black spot above it, followed by a discal series of obscure blackish spots.

The underside ground-colour is ochraceous yellow or a paler tawny yellow. The forewing paling to whitish on the apex, with the black markings as on the upper side but somewhat blurred and diffuse. The hindwing has a series of white spots traversing the black terminal margin. Antennae black, head and thorax black spotted with ochraceous and white.

The Tawny Coster has a wingspan of 53-64 mm.

The caterpillars are cylindrical, slender, with six longitudinal rows of fine branched spines; colour reddish brown with an oily gloss, much paler on the head, second and last segment. The pupa is perpendicularly hung, long, slender, smooth; two lateral angles on the thorax; head quadrate; colour creamy white, with broad longitudinal bars of purplish-black spotted with orange.

The Journey South is Complete
How this tenacious butterfly is able to slowly but surely make its voyage down all the way to Singapore from its origins in India and Sri Lanka is one of the wonders of the natural world. Using its ability to feed on a variety of host plants in the families Passifloraceae and Loganiaceae and probably a number of others, it has leapfrogged over land and survived predators and other dangers to cover a distance of many thousand kilometres to end up in Singapore.

Having now also been seen in Batam, it will surely try to continue its journey to Bintan in the Riau Archipelago, and who knows whether it will appear in the main Indonesian islands one day in the not too distant future?

But for now, Singapore has a new resident species - and a pretty and colourful butterfly at that, and this new "foreign talent" is likely to stay with us and be a part of the diverse flora and fauna of our little island in the sun.

Text and Photos by Khew SK

References :

  1. Wikipedia : Acraea terpsicore
  2. Malayan Naturalist (Magazine of the Malaysian Nature Society) Vol 49 No 3 : 1996
  3. The Malayan Nature Journal Vol 59 Part 1 October 2006
Post Note : Various lepidopterists in India are still debating on the actual scientific name of the Tawny Coster, preferring the precedent name of Acraea terpsicore to the more recent name Acraea violae. The jury is still out on the final name. For the time being, we have kept to the more commonly used scientific name of Acraea violae based on the more popular global references of Lepidoptera.

Update 2015 : The scientific name of this species has been adopted as Acraea terpsicore by several authors henceforth, and updated accordingly.