27 March 2021

Butterfly of the Month - March 2021

Butterfly of the Month - March 2021
The Perak Lascar (Pantoporia paraka paraka)

A Perak Lascar perched on the fruit of the Singapore Rhodendron

In a few days' time, the first quarter of the year will be over, with March 2021 ending on a relative positive note in Singapore, as far as the COVID19 pandemic is concerned. With daily infections in the low single digits within the community, the situation can be considered well under control. The national vaccination exercise is progressing well, as the invitation for citizens and residents in the next age group of 45 and 59 to be vaccinated went out at the beginning of this week.


The further lifting of restrictions on pandemic safety measures is a good sign that Singapore is gearing up for an eventual recovery and moving towards a new norm. Companies evaluate the prospects of workers going back to work once the government raises the limit of staff within the premises of offices to 75%. But with many staff working from home (WFH) for nearly a year now, will the workforce be happy to get back to the office?


Vaccination programmes being rolled out in many countries give hope that international borders will be opened for business and leisure soon. The pent-up demand for travel may soon see an end, as governments negotiate mutual recognition of vaccination 'passports' and travel bubbles between their respective countries.


Over in ASEAN, the Myanmar riots created cause for concern as the military used deadly force to contain the protesters in various cities across the country. Although each side has their own story to justify the coup against the democratically-elected civilian government, the use of firearms against largely unarmed groups of fellow citizens is something that is hard to comprehend.

A Perak Lascar perches on a leaf with its wings opened flat

Our Butterfly of the Month for March 2021 is the Perak Lascar (Pantoporia paraka paraka). This relatively small Nymphalidae is one of two extant species from the genus Pantoporia in Singapore, although a possible third species is still under investigation. The Perak Lascar is not uncommon, and frequently found near back-mangrove habitats where one of its caterpillar host plants, Dalbergia candenatensis (Leguminosae) frequently grows.


The species has the typical orange/black bands on the upperside of its wings, with the underside a paler orange-yellow. The unique diagnostic characteristic that separates the Perak Lascar from its lookalike cousins, is the pair of pale orange submarginal lines on the forewings above. One, or both the lines are often bent in space 3.

A mating pair of Perak Lascar.  Male - Left, Female - Right

The Perak Lascar has the usual flap-glide-flap flight characteristics, and is usually skittish and challenging to approach. It usually stops on the top surfaces of leaves with its wings opened flat to rest or sunbathe. Males have larger areas of orange compared to the black stripes, giving it a brighter orange appearance compared to the other lookalike species. Females have more distinct black outlines on its orange stripes on the underside.

A Perak Lascar feeding on the ripened fruit of the Singapore Rhododendron
A Perak Lascar puddling at a muddy footpath

The Perak Lascar is sometimes seen feeding on the ripened fruits of the Singapore Rhododendron (Melastoma malabathricum), or when Syzygium trees flower in the forested nature reserves of Singapore. Occasionally, males are also observed to puddle at damp footpaths in the forested areas. 


The caterpillars of the Perak Lascar have been bred on three host plants, namely Dalbergia candenatensis (Leguminosae), Dalbergia rostrata (Leguminosae), Cnestis palala (Connaraceae). The caterpillar of the Perak Lascar has the habit of cutting rachis and petiole of the leaf it resides on and using silk threads to attach pieces of cut lamina to the exposed midrib. Its diet consists mostly of the brown and withered leaf lamina created in this process.  For a small species, the early stages is unusually long - taking as many as over 40 days from egg to eclosion.

Text by Khew SK : Photos by David Chan, Khew SK,  Loh MY, Nelson Ong, Richard Ong, Horace Tan and Bene Tay


28 February 2021

Butterfly of the Month - February 2021

Butterfly of the Month - February 2021
The Burmese Sailor (Neptis leucoporos cresina)

A Burmese Sailor feeding on the ripened fruit of the Singapore Rhododendron

Today is the last day of February 2021. The Lunar New Year, heralding the Year of the Ox, has come and gone almost in a flash. The COVID19 situation in Singapore appears to be under control, with low daily infection numbers in the community. The vaccination programme is under way, and moving along pretty well without any major incidents. The government hopes to vaccinate the entire population by the end of the year, although vaccination is still voluntary.


The month of February has not been particularly auspicious, considering the number of fatalities. From 'preventable' site accidents to a major explosion in a factory that claimed the lives of three migrant workers, the number of fatal cases was extraordinary in a month. And then there was that accident where a speeding BMW crashed into a building in the early hours of the morning and burst into flames. The accident was reported as one of the worst in recent years where 5 men lost their lives.

A pristine Burmese Sailor sunbathing on a granite rock

And as if to add to Singapore's woes, the air quality in some parts of Singapore worsened. A grim reminder of the dreaded haze where air quality was so bad that much of the population had to stay indoors to avoid health issues. The hot dry season is here and the potential of fires burning out of control in neighbouring countries increases significantly. Let us hope that we will not get a repeat of the years where the PSI ratings hit the 'hazardous' range.

A mating pair of Burmese Sailors

Our Butterfly of the Month for February 2021 is a forest-dependent Nymphalidae, the Burmese Sailor (Neptis leucoporos cresina). One of four "Sailor" species found in Singapore, the Burmese Sailor is not uncommon, but usually sighted in the forested nature reserves and nature parks. This is probably due to the fact that the species' caterpillar host plant, Gironniera nervosa, G. subaequalis, and G. parviflora are all forest plants that are not normally found in urban parks and gardens.


Superficially similar to the Common Sailor and Short Banded Sailor, the Burmese Sailor is also one of the black-and-white striped species that can be difficult to identify in flight. The white median band on the underside of the hindwing in the Burmese Sailor does not reach the costa. The underside of both wings is greyish-brown and white, which distinguishes it from the orange-and-white underside of the Common Sailor and Short Banded Sailor.

A Burmese Sailor feeding on the ripened fruit of the Singapore Rhododendron

Sometimes also called the Grey Sailor, the species is sometimes spotted singly along forest paths, gliding amongst the shrubbery. It is skittish, and is not easy to approach. Both sexes are often spotted at flowering trees like Syzygium spp., and takes to the over-ripened fruits of the Singapore Rhododendron (Melastoma malabathricum).


The eyes of the Burmese Sailor are transparent and has a reflective blue-green hue. The upperside of the thorax and abdomen has an metallic coppery-green sheen, whilst the abdomen is always white-ringed next to the discal band on the hindwing.

A Burmese Sailor puddling at a damp forest footpath

Whilst it is more often seen feeding at flowering plants or at the over-ripened fruits of the Singapore Rhododendron, it is sometimes seen feeding on bird droppings on leaves in the forest, and also puddling at damp forest footpaths.

Text by Khew SK : Photos by David Chan, Chng CK, David Ho, Federick Ho, Khew SK and Jonathan Soong 

13 February 2021

Life History of the Angled Castor

Life History of the Angled Castor (Ariadne ariadne ariadne )



Butterfly Biodata:
Genus: Ariadne Horsfield, 1829
Species: ariadne Linnaeus, 1763
Subspecies: ariadne Linnaeus, 1763
Wingspan of Adult Butterfly: 38-45mm
Caterpillar Local Host Plant: Ricinus communis (Euphorbiaceae, common name: Castor Oil Plant)


An Angled Castor puddling on a wet ground.

A female Angled Castor perching on a leaf of the Castor Oil Plant.

A newly eclosed female Angled Castor resting in the vicinity of its pupal case.

Physical Description of Adult Butterfly:
On the upperside, the 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. 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 upper- and underside views of both male and female adults of the Angled Castor.

A male Angled Castor perching on the underside of a leaf.

A male Angled Castor perching on a flower of the Coat Buttons plant.

A sun-bathing Angled Castor perching on a grass blade.

Field Observations of Butterfly Behaviour:
Angled Castor was re-discovered in Singapore in 2013 when a single individual was observed in an area within the Central Catchment Reserve on mainland Singapore. More recently, in late 2018, a small colony of this species was found in a location on Pulau Ubin, in an area where its host plant, the Castor Oil Plant, grew in abundance. The slow flying adults could be seen feeding on grass flowers in that location, and puddling on damp muddy areas at that site.

An Angled Castor taking nectar from flowers of a grass species.

Another Angled Castor taking fluid from grass flowers.

A male Angled Castor perching on a twig.

An Angled Castor sunbathing on a leaf.

A female Angled Castor displaying its beautiful wing underside.

Early Stages:
Across the regions where Angled Castor occurs, the preferred larval host plant is the Castor Oil Plant (Ricinus communis) from the Euphorbiaceae family. This is also true in Singapore. In India, several Tragia species, also belonging to the Euphorbiaceae, have also been identified as larval host plants. Caterpillars in all instars of the Angled Castor feed on leaves of the Castor Oil Plant.

Local host plant: Ricinus communis (Castor Oil Plant).

A mother Angled Castor ovispositing on the leaf underside of the Castor Oil Plant.

Eggs of the Angled Castor are laid singly on the surface of a leaf of the host plant. The yellowish green egg is oval-shaped with a flat base, and a small flat top with the micropylar sitting in the middle. The surface is marked with rows of long, whitish hairs. Each egg has a height of about 0.8mm.

Two views of an egg of the Angled Castor, height: 0.8mm.

Two views of a mature egg of the Angled Castor. Note the head capsule and body setae now clearly visible through the egg shell.

The egg takes about 2.5 to 3 days to hatch. The young caterpillar emerges by eating a sufficiently large part of the egg shell. The newly hatched is about 1.6mm in length and it has a cylindrical and pale yellowish brown body covered with rows of long black setae (hair) dorsally and dorso-laterally, and white setae laterally. The body is also marked with several reddish brown patches laterally. The head capsule is pale brown to dark brown.

Two views of a newly hatched Angled Castor caterpillar soon after its emergence.

The 1st instar caterpillar feeds on the leaf lamina. As it feeds and grows, the lateral dark patches and the head capsule turn dark brown. After reaching about 3.5mm in 2-2.5 days, the caterpillar moults to the 2nd instar.

Two views of 1st instar caterpillar, length: 3.2mm.

Two views of 1st instar caterpillar, late in this stage, dormant prior to its moult, length: 3.5mm.

The body of the 2nd instar caterpillar is yellowish brown with dark brown lateral patches on most body segments. Moderately long tubercles, each of which is endowed with dendritic spines and setae, run along the length of the body. On each side of the body, there are three series of such tubercles: one occurs dorso-laterally, another laterally and the last sub-spiracularly. The colour of the tubercles on the metathorax, 3rd, 5th and 7th abdominal segments are dark brown, while those on the remaining body segments are yellowish brown. The head capsule is dark brown with two brownish cephalic horns, each of which is also endowed with dendritic spines and setae. This instar lasts about 1.5 days with the body length reaching about 5.5mm.

Two views of a 2nd instar caterpillar of the Angled Castor, early in this stage, length: 3.3mm.

Two views of a 2nd instar caterpillar of the Angled Castor, length: 4.5mm.

Two views of a late 2nd instar caterpillar of the Angled Castor, dormant prior to its moult, length: 5.5mm.

The 3rd instar caterpillar resembles the 2nd instar caterpillar closely, with the same three series of tubercles. These tubercles and associated dendritic spines are proportionately longer (than those in the 2nd instar) and uniformly dark brown in coloration. The body is mostly dark brown dorsally and laterally, except for the prothorax, the posterior segment and lower portion of each segment, which are yellowish brown. Tiny, whitish specks can be seen on the dark dorsum. The cephalic horns are also much longer proportionally and feature a number of lateral spines. The head capsule is completely dark brown to black. This instar takes about 2 days to complete with body length reaching about 8-9mm.

A newly moulted 3rd instar caterpillar of the Angled Castor.

Two views of a 3rd instar caterpillar of the Angled Castor, length: 7.3mm.

Two views of a late 3rd instar caterpillar of the Angled Castor, dormant prior to its moult, length: 8.8mm.

The 4th instar caterpillar closely resembles the 3rd instar caterpillar, but with dark coloration on the dorsum much more intense than in the 3rd instar, and the cephalic horns longer proportionately as well. The 4th instar lasts about 2.5-3 days with the body length reaching about 17-18mm. In late 4th instar, a band of small greyish white patches can be seen on the dorsum.

Two views of a 4th instar caterpillar, early in this stage, length: 9.6mm.

Two views of a 4th instar caterpillar of the Angled Castor, length: 15mm.

A 4th instar caterpillar of the Angled Castor found in the field on a leaf of the Castor Oil Plant.

Two views of a late 4th instar caterpillar, dormant before its moult, length: 16mm.

The 5th (and final) instar caterpillar is similar to the 4th instar caterpillar. As in the late 4th instar, a band of small whitish patches appear on the dorsum of the 1st to the 7th abdominal segments. The strong contrast between the white patches and dark coloration of the dorsum makes this band a striking and easy identifiable feature of the 5th instar. A noteworthy point: The base of the dorsal and dorso-lateral tubercles on the mesothorax, metathorax, and the 1st to 8th abdominal segments can be red in some individuals, or black in others.

A 5th instar caterpillar of the Angled Castor, newly moulted. Note the exuvia behind the caterpillar. The tubercles and cephalic horns still in the stage of expansion.

A 5th instar caterpillar of the Angled Castor, newly moulted. The tubercles and cephalic horns fully formed.

Two views of a 5th instar caterpillar, early in this instar, base of tubercles reddish, length:18mm.

Two views of a 5th instar caterpillar of the Angled Castor, base of tubercles reddish, length: 28mm.

Two views of a 5th instar caterpillar of the Angled Castor, base of tubercles black, length: 30mm.

A 5th instar caterpillar (base of tubercles red) found in the field on a leaf of its host plant, after a rain swept through the area.

The 5th instar lasts for 3-3.5 days, and the body length reaches up to 30-31mm. On the last day, the body becomes shortened and the caterpillar ceases feeding and wanders around. Eventually it stops at a spot on the underside of a leaf or a stem and spins a silk pad from which it hangs vertically to take on the pre-pupatory pose.

A pre-pupa of the Angled Castor.


The pupation event of a Angled Castor caterpillar.

Pupation takes place about 0.5 day later. The pupa suspends itself from the silk pad with no supporting silk girdle. It occurs in two color forms, with the brown form appearing pale yellowish brown with dark brown spots and patches on the dorusm, and the green form appearing pale yellowish green with dark green spots and patches on the dorsum. The dorsum of the thoracic segments are raised to tall ridge at the mesothorax. At the anterior end, there are two short cephalic horns. Length of the pupa: 20-22mm.

Three views of a pupa of the Angled Castor, brown form.

Three views of a pupa of the Angled Castor, green form .

Three views of a mature pupa of the Angled Castor.

After about 5 days of development, the pupal skin of the mature pupa turns translucent and the whole pupa becomes mostly dark brown at this stage. The eclosion event takes place the next day.


The eclosion event for both male and female Angled Castor.

A newly eclosed female Angled Castor resting on its pupal case in the field.

A newly eclosed male Angled Castor resting on its pupal case.

A newly eclosed female Angled Castor resting on its pupal case.

An interesting fact. All 5 instars of the Angled Castor larval stage have the habit of forcefully ejecting their frass pellets. This is not a common feature among butterflies. Previously, we have only observed this behaviour in members of the Ypthima and Mycalesis genera, as well as Discophora sondaica (Common Duffer).


Forceful ejection of frass pellets by caterpillars of the Angled Castor.

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.
  • K. Saji, H. Ogale and M. Bhakare. 2021. Ariadne ariadne (Linnaeus, 1763) – Angled Castor. Kunte, K., S. Sondhi, and P. Roy (Chief Editors). Butterflies of India, v. 3.06. Indian Foundation for Butterflies.
    http://www.ifoundbutterflies.org/sp/493/Ariadne-ariadne  
Text by Horace Tan, Photos by Loh Mei Yee, Khew S K and Horace Tan, Videos by Horace Tan.