Butterfly of the Month - June 2010

Butterfly of the Month - June 2010
Banded Swallowtail (Papilio demolion demolion)

As we cross into the month of June and head towards the middle of the year 2010, the International Year of Biodiversity, it has indeed been a busy half year for ButterflyCircle. The addition of a long-lost species to the Singapore Butterfly Checklist is one of the highlights so far, and we look forward towards the 300 species mark for Singapore.

The summer solstice normally falls on June 21st (sometimes the 20th). In the northern hemisphere this is the day with the most daylight. After this date the days begin to get "shorter". This is also the first day of summer.

Butterflies continue to be "in season" as the normally drier months of the year begin to make way for the winds where the South-West monsoons bring heavy rains to the region. For the first time in many years, even the famous Orchard Road in Singapore was flooded!

This month, we feature another member of the Swallowtail family, the Banded Swallowtail (Papilio demolion demolion). This fast-flying Papilionidae has black wings with a pale greenish macular band extending from the apex of the forewing to the mid-dorsum of the hindwing. The hindwing has a series of pale greenish lunulate submarginal spots and a black ocellus ringed with orange-red at the tornal angle. There is a long spatulate tail at the hindwing.

The butterfly can be found in the fringes of the nature reserves, flying erratically up and down sunlit paths. It is often observed flying from flower to flower, feeding on nectar from Ixora and Lantana flowers in a very hurried manner. In Singapore, males of this species are observed puddling only on infrequent occasions, unlike the typical behaviour of many other male Papilionidae species.

Although difficult to photograph when in full flight whilst feeding on flowers, a frequently observed habit of the Banded Swallowtail is that it stops to rest in shaded areas with its wings opened flat after a bout of active flying. This presents a good opportunity to photograph it if one is able to approach it stealthily without scaring it off. It is usually skittish and any sudden movements would definitely trigger it off into its high-speed flying routine again.

Males and females are generally similiar in appearance with the exception of the lunule in space 2 of the hindwing, where it is reddened in the female). A unique feature of this species is that the female lays her eggs on top of one another in the form of a rod. The caterpillars feed on at least two species of Rutaceae, of which one species is a Citrus. Unlike the majority of the Papilionidae, the early instars of the caterpillars of the Banded Swallowtail tend to feed gregariously and often move like a herd with the caterpillars following one another moving in single file, following the lead caterpillar.

The Banded Swallowtail can be considered moderately common in Singapore, although more often than not, only single individuals are encountered.

Text by Khew SK : Photos by James Chia, Sunny Chir, Goh LC, Federick Ho, Koh Cher Hern, Henry Koh, Loke PF, Nelson Ong & Mark Wong

Life History of the Branded Imperial

Life History of the Branded Imperial (Eooxylides tharis distanti)

Butterfly Biodata:
Genus: Eooxylides Doherty, 1889
Species: tharis Geyer, 1837
Subspecies: distanti Riley, 1942
Wingspan of Adult Butterfly: 34mm
Caterpillar Local Host Plants: Smilax bracteata (Smilacaceae)


A Branded Imperial taking a break on a leaf perch.


Another Branded Imperial on a leaf perch.

Physical Description of Adult Butterfly:

Above, both sexes are dark brown, with black confluent spots on the white tornal patch on the hindwing. In the male, the dorsal area on the forewing and the tornal area of the hindwing are lightly dusted in blue, and there is a dark circular brand around the origins of spaces 2, 3 and 4. Underneath, the wings are mainly reddish orange. The forewing is unmarked and the hindwing has large black submarginal spots on the white tornal area which is separated from the orange area with an irregular border outlined with black striae. Each hindwing is toothed at the end of veins 1b and 3, and has a long white tail at the end of vein 2.

Another Branded Imperial adult.

Field Observations of Butterfly Behaviour:

This species is rather common in Singapore, and the adults can be readily found in the Central Catchment Reserve, Bukit Timah Nature Reserve, western wastelands and Southern Ridges. Adults can be sighted rather frequently along forest paths, forest fringe or gaps, \with the adults sunbathing or flitting from perch to perch in the vicinity of its host plant. At times, adult butterflies can be observed to feed on plant sap at the caterpillar's feeding damage site on the Smilax shoot.

A Branded Imperial licking sap from a Smilax shoot where feeding damage has been made.


Another sap-licking Branded Imperial adult on a Smilax shoot.

Early Stages:

The Branded Imperial shares the same host plant, Smilax bracteata, with the Yamfly (Loxura atymnus fuconius). The caterpillars of both species feed on the young tender shoots of this woody climber, but for some unknown reason, Branded Imperial is the more common of the two species locally. The host plant is a woody climber with long, coiling stipular tendrils and long, stout stems which are covered with bristles and stiff prickles. It has a wide distribution in Singapore and its occurrence is typically accompanied by the presence of a population of the Branded Imperial.

Host plant : Smilax bracteata. Left: far view with the plant growing over another plant species.
Right: near view of leaves at a relatively young shoot.


A Young and fleshy shoot of Smilax bracteata.


A mating pair of the Branded Imperial.

Eggs are laid singly on the young shoots of the host plant. It is common for a number of eggs to be found on the same shoot. Each egg is white, hemispherical and has an elevated large ring atop surrounding a small and depressed micropyle. The surface is covered with many tiny pits which are barely visible to the naked eyes. Each egg has a basal diameter of about 1mm and a height of about 0.6mm.

Two views of an egg of the Branded Imperial.

It takes 3 days for the egg to hatch. The young caterpillar consumes the upper portion of the egg shell to emerge. With a length of 1.5-1.6mm, it has a yellowish head, long dorso-lateral setae on the mesothorax and the 7th abdominal segment and long lateral setae along the fringe of the body. The caterpillar feeds by scraping the external layer of the fleshy young shoot in all instars. It is initially whitish but turn yellowish after a few feeds.

1st instar caterpillars. Top: newly hatched, 1.5mm. Bottom: few hours old, length:1.7mm

Closer scrutiny reveals a prothoracic shield and a roughly rectangular anal palte in same pale yellowish coloration as the body base colour. The first instar lasts 3-3.5 days and with the body reaching about 3mm.

1st instar caterpillars. Top: 2mm, Bottom: 2.5mm.

The 2nd instar caterpillar does not have the long dorso-lateral setae on the mesothorax and the 7th abdominal segment as in the first instar. The body appears smooth to the naked eyes but its surface is actually covered with many tiny pits with minute setae emanating from each of them. The lateral setae lining the fringe of the body are also proportionately shorter than in the 1st inar. The body colour is yellowish with varying extent of pink to red shading. This instar lasts for 2.5-3 days and reaches a length of about 5.5mm.

2nd instar caterpillars. Top: 3.5mm, Bottom: 5.1mm

The 3rd instar caterpillar looks similar to the 2nd instar caterpillar but with a humpbacked thorax. The body colour varies from ochreous yellow to deep red. The dorsal nectary organ (DNO) on the 7th abdominal segment and the tentacular organs (TOs) on the 8th abdominal (just behind the last pair of spiracles) are now discernible. The body length reaches up to 11mm in this instar which lasts about 3-3.5 days.

3rd instar caterpillars. Top: 7.1mm, Bottom: 9.8mm.


Prothoracic shield (left) and anal plate of a 3rd instar caterpillar.

The 4th (and final) instar caterpillar resembles the 3rd instar caterpillar but with a more prominent hump on the thorax. Both the prothoracic shield and the anal plate are now rather conspicuous.


Two views of a 4th instar caterpillar, early in this stage, length: 13.5mm.


Two views of a 4th instar caterpillar, length: 16mm.


Prothoracic shield (left) and anal plate of a 4th instar caterpillar.

The 4th (and final) instar lasts 5-6 days and the body reaches a length of about 17-18mm. In the last day of this stage, the caterpillar ceases feeding, and its body shrinks in length. It wanders along the stem or branch of the host plant and finally comes to rest on a chosen spot. Here the caterpillar prepares for pupation by spinning a silk pad and a silk girdle to secure itself. It then becomes immobile in this pre-pupatory state for about 1 day.

Two views of a pre-pupa of the Branded Imperial

The next day the pupation takes place (see video clip below). The pupa is held via its cremaster and a silk girdle to the silk pad on the substrate. It is green in ground colour. Dark spots of variable sizes are featured on dorsum of the abdomen. The wing case is dark brown to black with varying number of whitish streaks/patches. Spiracules are yellow and prominent, especially the ones on the prothorax. Length: 11-13mm.

A video clip showing the pupation event of a Branded Imperial caterpillar.

Two views of a fresh pupa of the Branded Imperial

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

Two views of a mature pupa of the Branded Imperial.


A newly eclosed Branded Imperial resting near its empty pupal case.

Both the 3rd and 4th instar Branded Imperial caterpillars are truly myrmecophilous (live in association with ants) with their nectary organs attracting ants of various species to tend to them.

A final instar caterpillar of the Branded Imperial being attended by ants.


Branded Imperial caterpillars (how many can you spot?) receiving the attention of a giant ant (Camponotus gigas) on a young Smilax shoot. The adult butterfly is taking plant sap from the damaged part of the young shot.

In addition to DNO and TOs, the Branded Imperial caterpillars also possess a number of hair-derived glands, called pore cupola organs (PCOs), which are involved in myrmecophily. Ants have been observed to "lick" secretions from the DNO, and "harvesting" secretions from PCOs on various parts of the larval body.

Another shot of Branded Imperial caterpillars receiving the attention of the giant ant.


Branded Imperial caterpillars (red form) on a well eaten Smilax shoot.
Note the attending ants and eggs of the Branded Imperial.

References:

• Observations on the biology of Exooylides tharis. K. Fiedler, Nachr. entomol. Ver. Apollo, Frankfurt/Main, N.F. 14(4): 325-337, 1994
  
• 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 P.F. Loke, Anthony Wong, Mark Wong, Sunny Chir, Khew SK and Horace Tan

Observation Notes on the Variability of the Common Four Ring

Observation Notes on the Variability of the Common Four Ring
Aberration or Valid Species?

Many butterfly enthusiasts amongst the members of ButterflyCircle often get excited over observations of slight differences in the physical markings and colours of various butterfly species - wondering if it is a new or different species (or subspecies) and even hoping for the possibility of discovering something that is new to science! In urban Singapore, the latter is probably unlikely, because if there is a butterfly species still lurking around in our Singapore forests that is new to science, it would have long been discovered (of course, I'd be happy to be proven wrong!)

Indeed, with the many lookalikes, particularly in the Lycaenidae and Hesperiidae families of butterflies, and also proven with the discoveries and re-discoveries of many species that were thought to have gone extinct in Singapore, many ButterflyCircle members are always keeping a sharp lookout for unusual behaviour or butterflies that look slightly different from the norm.

In this blog article, I discuss my personal observations of the wide variations in the size and arrangement of the ocelli on the hindwing of the Satyrinae, the Common Four Ring (Ypthima huebneri). These observations are purely from my records of field photographs of this species that may begin to suggest the possibility of a distinct species (or perhaps a subspecies) of the Common Four Ring that could exist in Malaysia and Singapore.

A Common Four Ring where the ocelli are separated but those in spaces 2 & 3 are almost touching, but not contiguous

An example of the Common Four Ring where the tornal ocellus is contiguous with those in spaces 2 & 3

The Common Four Ring, like its larger cousin, the Common Three Ring (often referred to as a "Cinderella of Butterflies"), is as under-appreciated and more often than not, ignored by most butterfly watchers. Drab-coloured, unattractive and small, this species tends to keep close to the edges of forested areas where it discreetly goes about feeding on wildflowers or fluttering unassumingly amongst the grass.

The Common Four Ring is described as having greyish brown uppersides with a large subapical ocelli (eye spot) on the forewing above. The undersurface of both wings is greyish or pale buff brown with fine dark brown striations. The hindwing features four ocelli (if the two small tornal spots enclosed in a single yellow ring is counted as a single ocellus).

A Common Four Ring with the tornal ocellus and those in spaces 2 & 3 separated

With a number of years of observing this species in the field, and photographing them, I noticed that the arrangement and size of the ocelli on the hindwings fall into three main categories :

1. Where the ocelli in spaces 2 & 3 are large and contiguous, and usually also contiguous with the tornal ocelli.


2. Where the ocelli in spaces 2 & 3 are almost touching or contiguous but are separated from the tornal ocellus This seems to be by far the most typical of the majority of individuals of the species that I've encountered.


3. Where all the ocelli are separated.

A typical example of a Common Four Ring where all the ocelli - tornal ocelli and those spaces 2 & 3 are contiguous

I am quite confident that there will be other individuals of this species encountered that may display further permutations to these three categories, as this species and many of the others in this genus, display a wide variability in the sizes of the ocelli and at times even feature some extra ocelli in uncommon individuals.

A Common Four Ring where the tornal ocellus and those in spaces 2 & 3 are distinctly apart from each other. Also note the striations on the hindwing are more sparse than those of the other individuals shown here, giving the hindwing a much "paler" appearance.

In looking at these field shots (all taken in Singapore) and placing them side-by-side, a non-local observer may be excused if he concludes that there could be more than one species of the Common Four Ring here, particularly where the ocelli (and hence the physical appearance of the butterfly) are so distinctly different.

A strange individual of a Common Four Ring where the tornal ocelli and those in spaces 2 & 3 are distinctly apart, but the ocellus in space 3 is very much smaller, as well as a hint of another very small ocellus in space 4 as well!

One has to just turn the pages of the book "Butterflies of Thailand" by Pisuth Ek-Amnuay to conclude that there are more species of Ypthima in Thailand than have been recorded in Malaysia and Singapore. Although invariably, most books on South East Asian lepidoptera only depict a single species of the Common Four Ring, could there actually be more than one species or subspecies? Or are they just aberrations and variations of this single species? It is also pertinent to note that this species is only featured up to species level in many reference books - Ypthima huebneri. Could there be a subspecies in existence in Malaysia and Singapore that has yet to be documented? Or are these just seasonal variations i.e. dry and wet season forms?

An example of a Common Four Ring where the ocelli in spaces 2 & 3 are contiguous, but separated from the tornal ocellus.

Food for thought, and more research needed before those questions can be answered with a higher level of confidence. Observers should continue to scrutinise individuals of the Common Four Ring when out in the field, and record their observations for future reference.

Text & Photos by Khew SK

Further References :

• Classification of Ypthima - Copyright Markku Savela
• Ypthima huebneri on Wikipedia
• Ypthima huebneri on Siam Insect Zoo & Museum
  

Life History of the Striped Albatross

Life History of the Striped Albatross (Appias libythea olferna)

Butterfly Biodata:
Genus: Appias Hübner, 1819
Species: libythea Fabricius, 1775
Subspecies: olferna Swinhoe, 1890
Wingspan of Adult Butterfly: 55mm
Caterpillar Local Host Plants: Cleome rutidosperma (Capparaceae, common name: Purple Cleome, Fringed Spiderflower).


A female Striped Albatross visiting a flower of Bidens alba.


Another female Striped Albatross with its upperside revealed.

Physical Description of Adult Butterfly:
The forewing apex is acute in the male but rounded in the female. Vein 9 on the forewing of both sexes arises before the end of vein 10. The male has a pair of hair pencils between the 8th abdominal segment and the saccus (a male mating structure). Above, the wings are white with a dentate black border in the male, and heavily black dusted with several broad white streaks and a series of yellow submarginal spots on the forewing in the female. Beneath, the wings are white in the male and yellow dusted in the female. The veins are dark dusted. A yellow basal streak, broader and longer in the female than in the male, lies along the costa on each hindwing.


A male Striped Albatross in a open-wing posture on a leaf perch.


A male Striped Albatross puddling on a damp patch.

Field Observations of Butterfly Behaviour: Although common in countries such as India, Sri Lanka and Myanmar, the Striped Albatross only established itself in Singapore and Malaysia about 70 years ago. The species has become rather common due to the widespread occurrence of its local host plant, Cleome rutidosperma, which is a weed found in many areas. The fast flying adults are most active in sunny weather and frequently visit flowers for nectar. They can be found in open habitats such as fringe of the nature reserve, wastelands, grass fields and even in urban and residential areas. The males have the habit of puddling for mineral intakes.


A newly eclosed female Striped Albatross.


A male Striped Albatross visiting a flower of the Coat Button (Tridax procumbens).

Early Stages:
The host plant, Cleome rutidosperma, is a common herbaceous weed with violet-blue to pink flowers. The caterpillars of the Striped Albatross feed on the relatively young to middle-aged leaves as well as young shoots, stems and flower parts.

Host plant: Cleome rutodosperma.


A mating pair of the Striped Albatross.

A mother Striped Albatross laying an egg on its host plant.

The eggs of the Striped Albatross are laid singly on a leaf or flower part of the host plant. The egg is spindle-shaped and standing on one end with a height of about 1mm, about 2.5 times as tall as broad. It has vertical ridges and numerous transverse striations. The vertical ridges end in low projections encircling the micropylar. The color of the egg is initially white but changes to orange overnight.

Two eggs of the Striped Albatross.


Two maturing eggs of the Striped Albatross.

The egg takes about 2 days to hatch. The newly hatched has a length of about 1.8mm and has a yellowish orange head capsule. Its cylindrically-shaped body is also yellowish orange and featuring sub-dorsal, dorso-lateral and lateral rows of small tubercles running lengthwise. Each tubercle has a short setae emerging from the middle of it. The end of each setae bears a tiny droplet of fluid.

A newly hatched caterpillar eating its egg shell.

Two views of a 1st instar caterpillar, early in this stage, length: 2mm.

The newly hatched eats the empty egg shell for its first meal, and then moves on to eat the leaf lamina. The body takes on a strong green undertone with the intake of leaf diet. The 1st instar growth is fast paced and the body length reaches about 4mm. After about 1.5 days of the 1st instar, the caterpillar moults to the 2nd instar.

Two views of a late 1st Instar caterpillar hours before its moult, length: 3mm.

The 2nd instar caterpillar is yellowish green in body color with similar setae-bearing tubercles as in the 1st instar. In addition, there are nuermous small conical tubercles dotting the body surface.The head capsule has changed to pale yellow. Laterally, the body surface is covered in numerous light brown speckles which are only discernible with a close-up examination. The posterior end also two tiny and short pointed ends. This instar lasts about 1.5 days with the body length reaching 5.5-6mm.


Two view of a 2nd instar caterpillar, length: 4.5mm


Two view of a 2nd instar caterpillar, late in this stage, length: 5mm

The 3rd instar caterpillar resembles the 2nd instar caterpillar closely except for the appearance of a faint yellowish dorsal band and a stronger green undertone in the body color. The head capsule is now yellowish green. It is also easier to discern the two anal points. This instar takes about 1-1.5 days to complete with body length reaching about 9mm.


Two views of a 3rd instar caterpillar, length; 6mm.


Two views of a 3rd instar caterpillar, length: 8.5mm.

Again, the 4th instar retains all the features as the 3rd instar. In addition, a white lateral line appears sub-spiracularly, initially faint in appearance but becoming more prominent as growth progresses. Numerous fine setae moderately long appear laterally just below the white lateral lines. This penultimate instar lasts 1-1.5 days with body length reaching about 17.5mm.


Two views of a 4th instar caterpillar, early in this stage, length: 9.5mm.


Two views of a 4th instar caterpillar, late in thie stage, length: 17.5mm.

The 5th and final instar caterpillar resembles the 4th instar caterpillar closely. The many tubercles dotting the body surface are blue to dark blue, giving the body a speckled appearance. The green head capsule also carries numerous conical tubercles with some fine setae emerging from most of them. The 5th instar lasts for 2-2.5 days, and the body length reaches up to 33mm.


Two views of a 4th instar caterpillar, newly moulted, length: 17.5mm.


Two views of a 5th instar caterpillar, length: 24mm.


Two views of a 5th instar caterpillar, late in this stage, length: 33mm.On the last day of the 5th instar, the body of the caterpillar shortens and changes to a dull shade of pale green. It ceases feeding and comes to rest on the underside of the stem/stalk of the host plant or larger leaves of other plants in the vicinity. Typically the caterpillar shows a strong preference for a vertical or steeply inclined surface. Here the caterpillar spins a silk pad and a silk girdle to secure itself and then becomes immobile in a head-up pre-pupatory pose.

Left: The head of a 5th instar caterpillar.
Right: The anal points of a 4th instar caterpillar.

Two views of a pre-pupatory larva of the Striped Albatross.


Pupation takes place about 0.5 day later. The yellowish green pupa secures itself with the same silk girdle as in the pre-pupal stage, but with cremaster replacing claspers in attaching the posterior end to the silk pad on the stem. The pupa has a long, pointed, slightly curved cephalic horn which is yellow in colour. There is a prominent thoracic ridge which is sharply raised dorsally at thoracic segment 2, and is colored in white to yellow along the ridge line. The abdominal segments 2-4 are produced laterally into a pointed tooth at each side of the abdominal segment 2. Two lateral ridge lines, white mostly and twice interrupted with yellow, run from the abdominal segment 2 to the posterior end. Length of pupae: 21-22mm.

Two views of the pupa of a Striped Albatross.

Two views of the maturing pupa of a female Striped Albatross.
Right panel shows the pupa in more advanced stage of development.

Two views of the maturing pupa of a male Striped Albatross.
Right panel shows the pupa in more advanced stage of development.

After about 5 days of development, the pupal skin turns translucent as the development within the pupal case comes to an end. The markings on the forewing upperside become discernible and indicative of the gender of the soon-to-emerge adult. The following day, the adult butterfly emerges from the pupal case.

Newly eclosed Striped Albatross drying wings on their respective pupal case.
Left: female; Right: male.

References:

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

Text by Horace Tan, Photos by Benedict Tay, Henry Koh, Sunny Chir, Khew S K and Horace Tan