27 February 2010

Life History of the Large Dart

Life History of the Large Dart (Potanthus serina)

Butterfly Biodata:
Genus: Potanthus Scudder, 1872
Species: serina Plötz, 1883
Wingspan of Adult Butterfly: 32mm
Caterpillar Host Plants: Flagellaria indica (Flagellariaceae)

Physical Description of Adult Butterfly:
The Large Dart is the largest of all Potanthus species, approaching the size of a Telicota species. Above, markings are orange-yellow, with the spot in space 6 on the hindwing very small or absent, and the three apical spots are separate from the spots in spaces 4 and 5. Underneath, the markings carry an orange tinge, and the spot in space 5 on the forewing is not completely detached from that in space 6.

A female Large Dart.

A male Large Dart.

Field Observations of Butterfly Behaviour:
This species is only recently re-discovered and added to the Singapore checklist. Adult sightings have so far been made in multiple habitats such as wastelands, nature reserves and mangrove areas, where the host plant can be found growing. During these sightings, adults have been observed to carry out activities such as visiting flowers, sunbathing and puddling.

Early Stages:

Host plant: Flagellaria indica. Note the coiled leaf tips and white flowers.

The host plant, Flagellaria indica, is a climber with strong but slender stems. The leaves are linear-oblong and 8-25cm long. Usually, the leaf tip ends in a coiled tendril. Flowers are white and occur in a branched terminal panicle. This plant is common in open thickets near the sea and in the local nature reserves. The caterpillars of the Large Dart feed on leaves of this plant, and live in shelters made by joining edges of a leaf together with silk threads.

Leaf shelter construction by caterpillars of the Large Dart (3rd and 5th instar).

The eggs are laid singly on the leaf, either on the basal part or on the coiled tendril. Each hemispherical egg is creamy white with a slight yellow tinge. The micropylar sits atop. The surface is covered with many tiny pits, almost indiscernible to the naked eyes. The base diameter is about 1mm.

An egg of the Large Dart laid on the coiled leaf tip.

Two views of a "fresh" egg of the Large Dart.

Two views of a developing egg. The red markings appear on day 2.

Developing eggs. Left: showing a vague outline of the developing caterpillar.
Right: fully developed and nibbling away egg shell prior to emergence.

It takes 4-5 days for the egg to hatch. The young caterpillar eats just enough of the shell to emerge, and has a length of about 2.8mm. Its has a cylindrical body shape, rather short dorso-lateral and sub-spiracular setae and a tuff of long setae on the posterior end. The head capsule is black and there is a black "colar" on the prothorax.

Newly hatched 1st instar caterpillar, length: 2.9mm

The body is initially goldenrod in colour but changes to yellowish green after a few feeding sessions on the leaf. The newly hatched constructs its leaf shelter as one of its first tasks after the hatching. Between feedings, the caterpillar retreats to its shelter for rest and safety. By the time the caterpillar lies dormant in its shelter for the moult to the 2nd instar, its length has reached 6mm. The 1st instar takes about 2.5 days to complete.

1st instar caterpillar, late in this stage, length: 5.5mm.

The 2nd instar caterpillar is yellowish green in color and the short dorso-lateral and lateral setae are now absent. The anal plate still carries a few setae but these are not as long and prominent as in the 1st instar. The head is black in color and the black colar on the prothorax is retained. This instar lasts about 3 days with the body length reaching about 9.5-10mm.

2nd instar caterpillar. Lengths: 7mm (top); 9.5mm (bottom).

The 3nd instar caterpillar resembles the 2nd instar caterpillar closely in markings and coloration, with the exception that the head capsule now has elongated whitish patches running down each side of the "face". This instar lasts about 3 days with the body length reaching about 17mm.

3rd instar caterpillar, female, early in this stage. Length: 9mm.

3nd instar caterpillar, male, early in this stage. Length: 9mm.

The 4th instar caterpillar also resembles the 3rd instar caterpillar with the only visible change being the two lateral white stripes on the head capsule are now broader and more dominant. In addition, thin white outlines, in the shape of an inverted "Y", also appear within the central black marking. This instar lasts 2.5-3 days with the body length reaching up to about 22mm.

4th instar caterpillar. Lengths: 13.5mm (top); 16mm (bottom).

The 5th (and final) instar caterpillar has no visible change in markings or coloration from the 4th instar. This instar takes about 5 days to complete with the body length reaching about 35mm.

5th instar caterpillar. Lengths: 24mm (top); 32mm (bottom).

Towards the end of the 5th instar, the the body of the caterpillar shortens and its coloration changes to a translucent pale green. Soon it becomes dormant in its leaf shelter and enters the prepupatory phase which lasts for one day During this time period the body color of the pre-pupa changes to yellow, and a fair amount of silk threads and white waxy substance are deposited within the tight confine of the leaf shelter.

Two views of a pre-pupa of the Large Dart.

Pupation takes place within the tight leaf shelter. The pupa does not secure itself with any cremastral attachment nor any silk girdle. It is mainly yellow brown and has a rather long abdomen and a thorax. Length of pupae: 20-22mm.

Three views of a pupa of the Large Dart, length: 21mm

After 8 days, the pupa becomes mostly dark brown with yellow markings apparent in the wing pads. Eclosion takes place the next day.

Three views of a mature pupa of the Large Dart, shortly before the eclosion event.

A newly eclosed Large Dart.

  • The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society.
  • Butterflies of Thailand, Pisuth Ek-Amnuay, 1st Edition, 2006
Text and Photos by Horace Tan

20 February 2010

Two Skips and a Growl

Two Skips and a Growl
Updating the Singapore Butterfly Checklist to 294

The addition of these three species - two Hesperiidae and one Danainae to the Singapore Butterfly Checklist has been long overdue. The Checklist, which now stands at 294, dates back to the early 90's when Steven Neo first started his surveys with the National Parks Board. Having taking over the baton from the late 90's I have kept intact, all the species that Steven had earlier recorded - some of which have not been seen since the early 90's.

The addition of the two Skippers and a Tiger doesn't bring the checklist to a close. In fact, as ButterflyCircle has more and more 'eyes and ears' on the ground, it is likely that there will be more discoveries and re-discoveries in the coming years, particularly in the Lycaenidae and Hesperiidae families where there are numerous lookalike species.

The limitation of field observations and photographs taken of either the upper or underside of a lookalike species cannot be understated. Up to a certain extent, field identifications are possible, but where close scrutiny of both the uppersides and undersides and also males and females of a species to confirm the species' identification with a higher level of confidence, the collection of voucher specimens become necessary. Without the requisite collecting permits from the authorities, the addition of species that are hitherto not recorded would be impossible.

The family Hesperiidae comprises rather unattractive and moth-like species and often under-researched as far as butterflies are concerned. This may be why the majority of new species discovered fall into this family - both locally and also globally.

The Large Dart (Potanthus serina)

The first re-discovery is from the genus Potanthus. Comprising a genus that features a total of 13 species in the Malaysian butterfly fauna, of which 5 species have been recorded in the past, we have only documented the Lesser Dart (Potanthus omaha omaha) as the only extant species in Singapore.

We now record the existance of the Large Dart (Potanthus serina) with a high level of confidence, having bred the entire life history of this species, as well as scrutinised several specimens - both males and females from various locations. The early stages will be featured in an upcoming article in this blog.

The Large Dart was named Potanthus hetaerus serina in early references but recently updated to its current name of Potanthus serina. It is the largest of the species in the genus, attaining a wingspan of up to 32mm. A characteristic feature of this species is that the three subapical spots are separate from the spots in spaces 4 and 5, and are not completely dislocated at vein 6 where the spots in spaces 5 and 6 overlap and not completely detached . The veins are dark dusted on the upperside of the hindwings. On the hindwing beneath, the ochreous scaling is orange-tinged.

The species frequents grassy areas and has been found in the nature reserves as well as in mangrove areas. Like most of its other close relatives in the genus, it is a rapid flyer. It is often observed in shaded areas in the afternoons, with its wings folded upright. In the early morning hours, one can observe it displaying the usual skipper pose, with the forewings held at an angle whilst the hindwings are opened flat.

The Common Palm Dart (Telicota colon stinga)

The record of this species, one of three in this genus. Records of this genus show that there are six species in the Malaysian and Singapore region, of which three have been recorded. With the confirmation of this species, all three are now extant in Singapore.

The presence of this species has been overlooked all this time, primarily due to field observations of the lookalikes of the genus Telicota. The other two species, T. augias and T. besta bina have been recorded earlier with voucher specimens. This latest re-discovery would not have been possible without breeding the early stages as well as dissection of the genitalia of a bred male specimen by ButterflyCircle member Chan Soon Chye. Having the benefit of comparing the details of the genitalia with the reference diagrams in the Butterflies of Singapore by Corbet & Pendlebury, and the descriptions of the species, the Common Palm Dart is now re-instated to the Singapore Checklist.

The Common Palm Dart is a relataively large skipper, attaining a wingspan of up to 36mm. The yellow colour of the post-discal band on the forewing is continued along the veins towards the termen. The bluish-grey stigma on the forewing in the male is more conspicuous that in the other species.

It is another rapid flyer and males are often seen 'dogfighting' in the early hours of the morning, and then resting on leaves and grass blades in the usual Skipper pose.

Yellow Glassy Tiger (Parantica aspasia aspasia)

Sightings of this Danainae have been recorded in the past, but it was uncertain as to whether the individuals sighted were actually imported products of human agency or free-ranging immigrants straying into Singapore during the NE monsoon season when the north-easterly winds tended to bring species from the southern part of the Malay Peninsula into Singapore.

Another recent sighting of a female at Hort Park, feeding on the flowers of the Indian Heliotrope (Heliotropium indicum) prompted us to record this species as a re-discovery. Though documented in the early authors' checklists, this species appears to be more of a seasonal migrant rather than an extant species in Singapore. It is still a mystery why this species no longer appears with regularity in Singapore, like its common cousins, the Dark Glassy Tiger (Parantica agleoides agleoides) and the Blue Glassy Tiger (Ideopsis vulgaris macrina).

A female Yellow Glassy Tiger shot recently at the Hort Park

Perhaps the species' preferred host plant is no longer available? Or the habitats are unconducive for its permanent re-establishment in the Singapore environment? As it is a rather common species in the Malaysian forests, further research may help us reach a conclusion as to why this species is not able to stay on permanently. This is one of the species that could be the subject of a re-introduction programme together with NParks after the host plants are cultivated at strategic habitats around the island. The Life History of the Yellow Glassy Tiger, recorded by ButterflyCircle member LC Goh in Kuala Lumpur can be found here.

With these three additions, the Singapore Butterfly Checklist now stands at 294 species. The checklist is by no means complete, as new additions are to be expected as more and new information is available on our butterfly species. There have been many 'extinctions' but also many new discoveries of species that were not on the early authors' original checklists.

As we move into a new decade in 2010 and also celebrate the International Year of Biodiversity, let us look forward to more additions to the Singapore butterfly fauna and work to conserve the species that have already made Singapore home.

Text by Khew SK ; Photos by Khew SK, Bobby Mun, Horace Tan, Anthony Wong & Mark Wong

References :
  • The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition 1992, Malayan Nature Society.
  • Butterflies of West Malaysia and Singapore, W. A. Fleming, 2nd Edition 1983, Longman Press
  • The Malayan Nature Journal, Vol 59, Part 1, Oct 2006, Malaysian Nature Society

16 February 2010

Tigers and the Belimbing

Tigers and the Belimbing
Sg Buloh Wetland Reserve on a hot sunny Tuesday

It was a hot and windy day, and the searing heat seemed to chase even the most robust of butterflies into hiding. However, at a remote corner of the wetland reserve, was a clump of trees that provided much-needed sustenance to more than a dozen Blue and Dark Glassy Tigers.

The typical long bi-pinnate leaf arrangement of the Belimbing tree

The trees were flowering from the trunks, as is the normal case for this species of Camias (Averrhoa bilimbi) or the Belimbing as the locals call it. The Belimbing fruit is well-known for its sour and adicic taste. The species is a close relative of the Starfruit (Averrhoa carambola) another well loved fruit in South East Asia.

The attractive flowers of the Belimbing

The tree is native to Malaysia and Indonesia. The Belimbing is well known for its green 'papaya-shaped' fruits that grow to about 10cm long. Most of the time, the Belimbing is dropped into dishes that call for a tangy or sour taste, such as sambals, pickles and chutnies, and is a regular addition to Peranakan cuisine and many local Malaysian dishes. The juice of the fruit has many medicinal uses as well.

The fruits of the Belimbing hang straight off the branches and trunk of the tree

The Belimbing trees at SBWR have always been at this location, but this is probably the first time that I've encountered them flowering and fruiting in profusion. Lucky for the butterflies too, as the Blue and Dark Glassy Tigers seemed to be in season this period, and I stopped counting them during the walk after reaching a total of 30.

The red-purple flowers of the Belimbing are pretty and attractive in their own right. Unlike their sour fruits, I'm quite sure the nectar is sweet, as the butterflies were scrambling over each other, going for the fresher flowers on the tree.

Besides the dominance of the Glassy Tigers, other species that were also spotted around the tree that also stopped for a taste of the nectar were the Common Grass Yellow, a King Crow and an unidentified Arhopala which scooted off quickly as I approached it.

A Common Grass Yellow and Dark Glassy Tiger joining in the nectar feast at the Belimbing tree

The structure of the flower is such that the stamens and pistil extend outwards and I observed that as the butterflies' proboscis reached deep into the flower for nectar, the body and legs of the butterflies were doing their work in pollinating the flower.

Pollinating the flower whilst feeding on nectar

From the photography viewpoint, shooting the rather drab-coloured 'tigers' complemented with the strongly coloured flowers of the Belimbing added a nicer dimension to the otherwise boring butterfly in terms of colour balance and composition.

Text and Photos by Khew SK

Further Reading :

References :
  • The Concise Flora of Singapore : Gymnosperms and Dicotyledons by Hsuan Keng 1990, Singapore University Press

13 February 2010

Life History of the Archduke

Life History of the Archduke (Lexias pardalis dirteana)

Butterfly Biodata:
Genus: Lexias Boisduval, 1832
Species: pardalis Moore, 1878
Subspecies: dirteana Corbet, 1941
Wingspan of Adult Butterfly: 90mm
Caterpillar Host Plants:
Cratoxylum cochinchinense (Hypericaceae, common name: Yellow Cow Wood), Cratoxylum pruriflorum (Hypericaceae).

A male Archduke perching on a leaf on the side of a forest trail.

A male Archduke displaying its wing upperside.

Physical Description of Adult Butterfly:

Above, the male is dark velvety black above with a broad greenish-blue distal border on the hindwing, which is continued narrowly along the termen of the forewing. The larger female is dark brown, and profusely spotted with yellow. Underneath, the male is deep ochreous brown with yellow spots. The female is dark brown on the forewing and pale grayish green on the hindwing; with both wings spotted with white. The apical portion of the antennal club is orange in both sexes.

A female Archduke found feeding among leaf litter in the nature reserve.

Another female Archduke resting on a dry leaf in the nature reserve
Field Observations of Butterfly Behaviour:
The Archduke is relatively common in the nature reserves. Adults are typically sighted on shaded trails and among undergrowth, and are seldom seen in open sunny areas. It is mainly a forest dweller and adults are often seen puddling on damp ground, or feeding on rotting fruits and other organic matter amongst forest litter. Refer to this earlier ButterflyCircle's blog article for a more detailed write-up on this species.

Early Stages:
The host plant, Cratoxylum cochinchinense, can be found growing naturally in the nature reserves and planted as wayside trees in various urban parks. It has simple and opposite leaves which are red to dark red when young. Its red bark can peel off in strips or angular pieces. The bisexual flowers are pinkish to darker red. Besides Archduke, this plant is also utilized by Short Banded Sailor and Common Grass Yellow as larval food plant. Caterpillars of Archduke feed on older and more mature leaves of this plant.

Host plant : Cratoxylum cochinchinense Leaves (left) and flowers (right).

A mating pair of the Archduke on forest ground.

The eggs are laid singly on the underside of a leaf of the host plant. Each egg is dome-shaped with a base diameter of about 1.8mm. The surface is covered with large irregular hexagonal depressions with hair-like protuberances emerging from adjoining corners. The tip of each "hair" carries a tiny fluid droplet. The color is initially dark green but turns purplish brown on day 2.

Two views of an egg of the Archduke on day 1.

Two views of an egg of the Archduke, one day prior to hatching.

After about 4 days, the 1st instar caterpillar emerges and proceeds to eat the eggshell as its first meal. The caterpillar is yellowish orange in body colour and has a head capsule in darker shade of yellowish-orange. Its body sports ten pairs of short dorso-lateral protuberances complete with long black setae. Frass pellets are usually seen attached to the tip of these setae in this instar. The caterpillar grows from an initial length of about 2.5mm to 7mm in three days. The subsequent moult takes it to the 2nd instar.

Newly hatched 1st instar caterpillar eating its own egg shell, length: 2.5mm.

1st instar caterpillar, length: 6mm

The moulting event of an Archduke caterpillar from 1st to 2nd instar at 6x speed.

The body of the 2nd instar caterpillar is predominantly orangy brown. All ten pairs of short protuberances seen in the 1st instar have lengthened considerably. Each is projected horizontally with numerous branched spines and is almost always pressed to the leaf surface. Each protuberance is mainly pale yellowish in color with some spines colored black in the middle and the tip portion. The 2nd instar lasts for three days with the body length reaching about 11mm before the moult to the 3rd instar. When alarmed, the caterpillar (both in this and later instars) typically reacts by curling up its body, and hiding its head under the "umbrella" of spines so creaed. (Note: all body lengths given in this article do not factor in lengths of the protuberances, and will simply give the length from the head capsule to the last body segment.)

Two views of 2nd instar caterpillar, length: 8mm

A 2nd instar caterpillar of the Archduke, length: 8mm

A 2nd instar caterpillar adopting a defensive stance, length: 8mm

The 3rd instar caterpillar is still orangy brown in body color. The protuberances have all become much longer in proportion. The branched spines appear almost like a bird's feather, with the secondary spines arranged neatly around the main spine. The tip section of the main spine is colored in brighter shade of yellow compared to the rest of the protuberance. Dorsally there are two long and thin bands, in much lighter shade of orangy brown. The 3rd instar lasts for 4-5 days and reaches a length of about 16-18mm before the next moult. Towards the end of this instar, the body color gradually changes to pale yellowish green.

3rd instar caterpillar adopting an defensive stance, early in this stage.

3rd instar caterpillar, length: 14mm

3rd instar caterpillar, late in this stage, length: 16mm

The 4th instar caterpillar has similar appearance as in the 3rd instar but with a pale yellowish green body color. Branched spines on each long protuberance are mostly pale green with just a few black in color scattered along its main axis. The few spines at the tip portion are all black. The distal portion of the protuberance is colored yellowish orange. As the caterpillar grows in this stage, the portion lying below this orange end will assume a strong bluish tone. On the body, the two dorsal lines are now more prominently marked, and are more constricted where adjacent body segments join. After 6-7 days in this instar, with its length reaching 28-30mm, the caterpillar moults to the 5th and final instar.

A 4th instar caterpillar which has just shed its old skin. length: 16mm

Three views of a 4th instar caterpillar, early in this instar, length: 16mm

4th instar caterpillar, length: 28mm

The moult from 4th to 5th instar of an Archduke caterpillar at 6x speed.
Part 1/2: shedding the old skin.

The moult from 4th to 5th instar of an Archduke caterpillar at 6x speed.
Part 2/2: inflating the new set of spines.

Essentially similar to the 4th instar caterpillar, the 5th instar features a brighter shade of green, especially so on the basal halves of the protuberances. It has also acquired a ferocious appetite, finishing one or two large leaves in a day.

5th instar caterpillar, newly moulted.

5th instar caterpillar, late in this stage, length: 49mm.

This final instar lasts for 8-9 days with the caterpillar reaching a mature length of about 50mm. On the last day, its body becomes shortened but hardly decolorized. It then seeks out a spot on the midrib on the underside of a mature leaf and stays put. There it laboriously spins large quantity of silk threads to make a silk mound, to which its posterior claspers are then attached to, typically with pre-pupa in an upside down posture. The dorsal lines disappear at this juncture and a whitish saddle mark can be seen on the 2nd abdominal segment.

Two views of a pre-pupa of the Archduke.

After 1 day of the pre-pupal stage, pupation takes place with the pupa suspended with its cremaster firmly attached to the silk mound on the midrib. The pupa is smooth and tapers steeply towards each end from a high transverse dorsal ridge which is lined with brown and a broader beige-colored transverse band. The light green pupa has a series of beige-colored spots symmetrically arranged. Two short cephalic horns, beige-colored with a brown patch, are also featured. Length of pupae: 26-28mm.

The pupation event of an Archduke caterpillar at 8x speed.

Two views of a pupa of the Archduke.

Ten days later, the pupa becomes considerably darkened, signaling the end of the development of the adult still encased within. The next day, the adult butterfly ecloses and stays near the empty pupal case for an hour or two before taking off to continue its life circle.

Two views of a mature pupa of the Archduke.

A newly eclosed male Archduke resting near its empty pupal case.

  • The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society.
  • Butterflies of Thailand, Pisuth Ek-Amnuay, 1st Edition, 2006
Text by Horace Tan, Photos by Henry Koh, Mark Wong, Khew SK and Horace Tan