Butterflies of the Singapore Botanic Gardens

Butterflies of the Singapore Botanic Gardens

Late last year, I had the honour of being invited to write an article about the butterflies of the Singapore Botanic Gardens in the SBG Newsletter - Gardenwise. This was the second time that I had written for the Gardenwise, the first time being in Volume 17 published in July 2001. Another article published after ButterflyCircle's "Butterflies Thru' the Lens" exhibition at the SBG Visitor Centre appeared in Volume 27 in July 2006.

So, after an eight year absence, the article Butterflies of the Singapore Botanic Gardens was published in Volume 32 Jan 2009 issue of Gardenwise.

The Gardens is one of my favourite sanctuaries when I need to get away from stressful situations at work, and a walk amongst the lush greenery and abundance of nature is very often a therapeutic stress-reliever. The Gardens hosts one of the largest collections of plants – both native and exotic, in Singapore. The bird life (see Gardenwise 30 (2008) 14-19) is healthy, with over a third of the total number of species seen in Singapore occurring here.

Amongst the plants and flowers of the Gardens, insect life is equally abundant. A casual observer will surely encounter a number of butterflies frolicking in the sunshine, busily feeding at flowers or just lurking around in the shaded understorey of the Rainforest at the Central Core of the Gardens.

This is the first attempt at compiling a checklist of butterflies of the Butterflies of the Singapore Botanic Gardens Gardens. Whilst there have been many observations and personal checklists made by enthusiasts and visiting experts, it would be ideal to maintain a repository of sightings, preferably with photographs. Over the years, I have kept a personal checklist of the butterflies that I’ve observed whenever I visit the Gardens, and also sightings made by other enthusiasts and observers, some of whom have kindly sent photographs of butterflies that they have encountered.
The list will, undoubtedly, keep growing as new species are found.

Butterflies can be rather choosy about their habitats, and being rather plant specific, many butterfly species are usually found more often in the vicinity of their caterpillar host plants. For example, the recent cultivation of Aristolochia acuminata and Passiflora foetida has brought in showy species like the Common Birdwing, Common Rose (and its subspecies, the Black Rose) as well as recent immigrants like the Leopard Lacewing and the Tawny Coster. The collection of Zingiberaceae and Palmae in the Gardens has attracted the skippers – Hesperiidae, of which a few species are rare and not often seen elsewhere. The caterpillars of the Hesperiidae create leaf shelters out of their host plants, and hence can often be easily spotted (and dispatched) by a sharp-eyed gardener who would consider these pests!

Two rare species which are noteworthy enough for special mention are the Orange Tail Awl (Bibasis sena uniformis) and the Blue Nawab (Polyura schreiber tisamenus). The former was a recent discovery for Singapore where it was found in the forested areas of the Central Catchment Reserves. Hence it came as a surprise to me when a small colony of caterpillars was found in the Gardens feeding on a common ‘wild’ shrub near the Tanglin Core. I have personally not seen an adult butterfly of this species in the Gardens, but upon breeding the caterpillars to adulthood, it was confirmed that the species is indeed the Orange Tail Awl.

The Blue Nawab is another curious resident of the Gardens. A rare species in Singapore, the caterpillar of this species was originally recorded on rambutan (Nephelium lappaceum) but subsequently recorded by ButterflyCircle members on the red saga (Adenanthera pavonina), a Bauhinia species (along the trellises near Les Amis Au Jardins), and on the exotic but common Australian wattle (Acacia auriculiformis). It has been sighted regularly in the Gardens, and some years ago I was having a meeting on the 2nd storey of one of the bungalows when a Blue Nawab decided to stop and rest on a tree branch just outside the window!

Another species to look out for is the Bamboo Tree Brown (Lethe europa malaya) which was spotted at the bamboo collection at the Bukit Timah Core. It is a rare species which is usually active only in the early hours and late hours of the day. A surprising find in the Gardens was the Courtesan (Euripus nyctelius euploeoides) of which a male was spotted some time back by Dr Ian Turner who emailed me a photo taken whilst on a routine walk around the Gardens. Even the parasitic plant Dendrophthoe pentandra which grows innocuously on its hosts’ branches way up in the treetops supports a number of beautiful butterfly species like the Painted Jezebel (Delias hyparete metarete), Green Baron (Euthalia adonia pinwilli) and a number of beautiful Hairstreaks like the Peacock Royal (Tajuria cippus maxentius).

The other species in the checklist are predominantly urban butterflies that are relatively common in Singapore, but nonetheless contribute life and variety to the Gardens. As butterflies are mobile and some species can fly long distances in search of both nectaring and caterpillar host plants, it is beyond doubt that more species will be added to the checklist as time goes by, adding to the biodiversity and colour of the Gardens.

Text by Khew SK ; Photos by Khew SK

Acknowledgments : Special thanks to Director/SBG - Dr Chin See Chung, and General Manager/SBG - Dr Wong Wei Har.

(This article appeared in the Feb 2009 Volume 32 of the Singapore Botanic Gardens Newsletter - Gardenwise on pages 18-20)

Download a PDF copy of Gardenwise here.

Butterfly Predators - Death in the Wind

Butterfly Predators - Death in the Wind

A Robberfly, a vicious and efficient killing machine, impales a No Brand Grass Yellow and perches with its prize kill whilst sucking the nutritious juices out of the paralysed butterfly

It is quite well-known that butterflies are harmless insects that do not bite, sting, scratch or cause any harm to other animals. They are therefore vulnerable to the wide variety of predators in the animal world. Whilst many butterfly species have adapted themselves with survival strategies (which will be the subject of a future blog article here), they are still susceptible to ending up in the stomachs of various birds, animals and insects which prey on them.

A pair of Chestnut Headed BeeEaters with one Jamides sp. captured

Most observers will notice butterflies fluttering around flowers, frolicking in the sunshine, feeding, mating and going about their usual daily activities. However, dangers always lurk where the butterflies don't realise... until it's too late. Predators adopt a whole range of tactics to capture the unsuspecting butterflies - stealth, speed, surprise, traps and so on.

A dragonfly captures a Lycaenid

A butterfly's life is therefore fraught with dangers as they go about their daily routine. In this article, we feature a range of predatory attacks on butterflies by various predators. It is never a pretty sight to see any victim of a predator in the animal world, and even though the death of a butterfly comes with much less blood and gore, it is still nevertheless a pitiful sight, as the poor butterfly struggles for its last breath of life in the jaws of its nemesis.

A dragonfly with a Lycaenid prey in its jaws

The first category of predators use a combination of speed and stealth. These predators - birds, dragonflies, mantises, lizards, robberflies and wasps tend to wait till the unsuspecting prey comes close enough for the predator to launch a high speed attack on the butterfly. Very often, these attacks are not necessarily successful, and the butterfly escapes with a part of its wings torn off, or in some cases, the predator misses altogether when the butterfly makes a last-minute maneuver to get out of harm's way.

A mantis rips the head off a Tawny Coster whilst chewing up the body

The next group of predators combine stealth with poison - e.g. the Crab Spider. These masters of camouflage are often seen hiding amongst flowers and waiting for a hapless butterfly to fly close enough to be grabbed and bitten. The poison of these spiders appear to act swiftly, immobilising the prey within a few seconds, and paralysing the butterfly quickly as the spider sucks the life out of it.

A Crab Spider holds on tightly to an immobilised Nigger


Another Crab Spider, well camouflaged amongst the flowers of Pseuderanthemum sp, with a dead Centaur OakBlue in its jaws

Predators which use entrapment - usually web-weaving spiders of various species, often trap the unsuspecting butterflies that fly into the sticky web and get themselves entangled. From field observations, the butterflies that get themselves into this life-ending situation are those that are old and weathered. The stronger butterflies often have a chance of flapping violently and we have seen many that have escaped the jaws of the spider in good time, before the spider can sink its fangs into the butterfly.

A Golden Orb Spider makes a meal out of a trapped Great Eggfly


A spider drags a paralysed Palm Bob to its lair

In the natural world, the weak and old are often fair game for most predators. Once a butterfly is old, tattered and flying erratically due to injury or old age, they become easy prey to various predators which help end their lives swiftly and viciously.

A wasp rips apart a dead butterfly

Whilst an adult butterfly's life is always subject to dangers from predators as it goes about its daily activities, its early stages are also vulnerable to a variety of parasitism, particularly at the egg, caterpillar and pupa stages . Parasitic wasps and flies can often wipe out an entire clutch of eggs and experts often estimate that, in the wild, anything between only 1-5% of all the eggs that a single female lays in her lifetime produces the next generation of adult butterflies. The majority of the rest will perish due to predation and parasitism.

Even caterpillars are not spared. Here, the caterpillar of a Mottled Emigrant falls prey to Kerengga ants (Oecophylla smaragdina)


A Commander caterpillar with parasites on its body

A caterpillar surrounded by the pupae of parasites

Whenever we encounter a pretty butterfly fluttering amongst flowers and we admire its beauty and grace, we should always be reminded that these 'flying jewels' of the insect world are always in danger of ending up dead in the jaws of a predator in the next few moments.

Indeed, one can always argue that the biggest 'predator' may also be Man himself, as the destruction of habitats and the spraying of pesticides often kill far more butterflies in all stages of their life histories than any other predator can. As we take stock of our biodiversity in Singapore, and as more species are threatened by a variety of causes, there should be a strategy for the conservation of habitats and sanctuaries for our butterfly fauna to survive for our future generations to enjoy.

Text by Khew SK ; Photos by Con Foley, Chan SC, Horace Tan, Marcus Chua, Michael Lim, John Lee, Henry Koh, Jason Ng & Khew SK

Life History of the Plain Nawab

Life History of the Plain Nawab (Polyura hebe plautus)

Butterfly Biodata:
Genus: Polyura Billberg, 1820
Species: hebe Butler, 1866
Subspecies: plautus Fruhstorfer, 1898
Wingspan of Adult Butterfly: 65mm
Local Caterpillar Host Plants: Adenanthera pavonina (Red Saga), Falcataria moluccana (Albizia), Parkia speciosa (Petai), all belong to the family Leguminosae, sub-family Mimosoideae.

Physical Description of Adult Butterfly:
The forewing has a strongly arched costa, a pointed apex and a concave termen. The hindwing has a pair of short stubby tails. Above, the Plain Nawab is greenish white and the forewing has a broad black border decreasing markedly from the apex towards the tornus and base of the costa, and a moderately large greenish white spot in space 5. The hindwing has a series of marginal spots. The Singapore subspecies of P. hebe, represented by the race plautus, is different from its Malaysian cousin P. hebe chersonesus in having a broad black border on the hindwing. Beneath, the Plain Nawab has a large, pale silvery-green median patch covering about a quarter of the wing. The broad wing borders are mainly brown to dark brown in color.


Another Plain Nawab found perching on a leaf in a hill park


A Plain Nawab perching on a leaf with open wings.

Field Observations of Butterfly Behaviour: The adults are medium-sized, heavy-bodies butterflies with rapid, strong and sometimes erratic flights. It has a habit of perching high on a spot in a tree, and keeps returning to the same perch after making swift flights in the vicinity to chase intruders away. The adults have also been observed to puddle on wet ground, carrion, faeces and tree sap. Plain Nawab is relatively common and widely distributed in Singapore, with frequent sightings made in both the nature reserves and Southern Ridges.


A Plain Nawab feeding on tree sap


A Plain Nawab puddling on wet ground in the nature reserves

Early Stages:
The early stages of the Plain Nawab have been locally observed to feed on leaves of three plants in the Leguminosae family. Of the three, the Red Saga is most popularly utilized with regular sightings of caterpillars on young saplings in Southern Ridges where the plant is commonly planted. Red Saga can grow to a rather large tree. Its leaves are bipinnate, with 3 to 6 pairs of side stalks, and 9 to 15 leaflets on each side stalk. The seed pods are curved and scarlet seeds.


Host plant : Adenanthera pavonina

A mating pair of the Plain Nawab

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A mother Plain Nawab laying an egg on Red Saga in a hill park.


Left: fresh egg; Right: mature egg with a glimpse of the head capsule

The egg takes 4 days to hatch, and the newly hatched has a body length of about 3-3.5mm. The young caterpillar eats the entire egg shell as its first meal. Its body is initially creamy yellow but turning green a day or two later. It has a black head with 2 pairs of horns, the lower of which being shorter and straight, and the upper one being longer and curved. There is also pair of biege anal processes. Between feeds, the young caterpillar rests along the midrib near the leaf tip on the upperside. From this "base camp", the caterpillar ventures out to feed on nearby leaflets. Larger caterpillars in later instars spin a silk mat across several leaflets in order to provide a sufficiently large "base" on which to rest.


Two views of a newly hatched Plain Nawab caterpillar, length: 3.5mm


Left: Two Plain Nawab caterpillars (in early 1st instar) sighted resting on the upper surface
of Red Saga leaves in the Southern Ridges.
Right: A close-up view of one caterpillar in the left panel.

After 4-5 days of feeding, the 1st instar caterpillar grows to a length of about 6.5-7mm. The caterpillar stays dormant in its base camp with the new head capsule growing progressively larger behind the current one. The caterpillar moults to the next instar about half a day later.
1st instar caterpillar, late in this stage, length: 6mm.

Besides the increase in size, in particular the head capsule, the 2nd instar caterpillar has similar appearance as the 1st instar caterpillar. After five days in this instar, and having the body length increased to about 12mm, the caterpillar moults again.


Newly moulted 2nd instar caterpillar with old head capsule nearby, length: 6.5mm



A 2nd instar Plain Nawab caterpillar resting in its "base camp" on the upper surface
of a Red Saga leaf in the Southern Ridges.

The head capsule of the 3rd instar caterpillar is pale yellowish brown with wide vertical streaks in dark brown. The pair of anal processes has become shorter in length and prominence. Light yellowish stripes fringes the body just below the spiracles on the abdominal segments. This instar takes 4 to 5 days to complete with body grown to about 16-17mm in length.


Three views of a 3rd instar caterpillar, length: 15mm

The head capsule of the 4th instar caterpillar is yellowish green with two pairs of stripes in darker green. This instar lasts a further 8-9 days with body length reaching about 25-26mm. In the last few days of the instar, pale green crescent marks start to appear on each body segment, giving us a hint of what the next instar will bring.


Upper left: late 3rd instar; Lower right: newly moulted 4th instar;
Right: head capsule of the 4th instar caterpillar


Two views of a 4th instar caterpillar, length: 23mm


A late 4th instar Plain Nawab caterpillar resting on a "base camp" built from joining several
adjacent leaves of the Red Saga. Found in the Southern Ridges.

The 5th instar caterpillar closely resembles the 4th instar. The most noticeable change is the silvering green crescent marks which stand in stark contrast to the dark green base color. The pair of anal processes is so small that the anal segment takes on a near rectangular outline.


5th instar caterpillar, newly moulted, length: 22mm


5th instar caterpillar, late in this stage, length: 48mm


Head capsule of the 5th instar caterpillar

The 5th instar lasts for 10-13 days, and the body length reaches up to 48-50mm. Toward the end of this instar, the body gradually shortens in length. The fully grown caterpillar soon abandons its "base camp" and goes in hunt for a pupation site. Eventually the caterpillar comes to rest on a spot on the under surface of a stem. There it spins a silk pad to which it attaches its claspers (anal prolegs). The pre-pupatory larva then hangs vertically, typically with its body curled up.

A pre-pupa of the Plain Nawab in its curled up posture

Pupation takes place a day later. The pupa suspends itself from the same silk pad but now with its cremaster. The pupa has a berry like appearance with its thick and cylindrically oval shape. It is green but streaked with abundant white and features a broad head. Length: 17-19mm.

A time-lapse sequence of the pupation event for one Plain Nawab caterpillar


Three views of a berry like pupa of the Plain Nawab.

The pupal period lasts for 9 days, and the pupa turns dark to reddish brown the night before eclosion. The large pale green patches on the forewings also become visible through the pupal skin at this stage.


Three views of a mature pupa of the Plain Nawab.

Eclosion takes place the next morning. The pupal case first cracks open with the adult butterfly making its way out. It quickly turns around and perches on the underside of the pupal case to "dry" and expand its wings. A few hours later, the adult butterfly makes the first flight of its life.

A time-lapse sequence of the eclosion event for one Plain Nawab caterpillar


A newly eclosed Plain Nawab

References:

• 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 by Horace Tan, Photos by Benedict Tay, Khew SK and Horace Tan