Saturday, September 28, 2013

Life History of the Large Snow Flat

Life History of the Large Snow Flat (Tagiades gana gana)

Butterfly Biodata:
Genus: Tagiades Hübner, 1819
Species: gana Moore, 1866
Sub-species: gana Moore, 1866
Wingspan of Adult Butterfly: 38-45mm
Caterpillar Local Host Plants: Dioscorea pyrifolia (Dioscoreaceae), Dioscorea orbiculata var. tenuifolia (Dioscoreaceae) and other Dioscorea spp.

Physical Description of Adult Butterfly:
Above, the wings are brown with obscure post-discal and discal spots in darker brown. On the forewing, there are three white hyaline sub-apical spots in spaces 6,7,8. On the hindwing, the tornal area is whitened and there are black marginal spots at the end of veins 2, 3 and 4, and in some specimens, another spot at the end of vein 1b. Below, the wings are similarly marked as per above but with the whitened area on the hindwing extended to the basal area and almost to the costal margin.

Field Observations of Butterfly Behaviour:  
This species is common in Singapore and can be found in the forested areas in the Central Catchment and Bukit Timah nature reserves, and several other sites across the island. The adults are rapid flyers and are more active in the cooler hours of the day. As is the case for the other Tagiades species, the adults have the habit of perching on the underside of a leaf between flights, and with wings opened flat. The adults are often seen visiting flowers for nectar.

Early Stages:
Several Dioscorea spp. have been found to be the local host plants for the Large Snow Flat. Only two of them have been formally identified. The caterpillars of the Large Snow Flat feed on leaves of the host plant. When not feeding, the caterpillars seek safety and concealment in a leaf shelter formed by cutting and folding a leaf fragment along the edge of the leaf.

Local host plant #1: Dioscorea pyrifolia.

Local host plant #2: Dioscorea orbiculata var. tenuifolia.

Leaf shelter of a 2nd instar caterpillar of the Large Snow Flat.

A mating pair of the Large Snow Flat.

The eggs of the Large Snow Flat are laid singly on the underside of a leaf of the host plant. The pale yellowish is hemispherical with surface marked with longitudinal ridges running from the pole to the rim of the base. The egg is well concealed in a mass of fine whitish to pale yellowish setae deposited by the mother butterfly. Each egg has a diameter of about 0.9mm.

Two views of an egg of the Large Snow Flat.

Left: a maturing egg; Right : a mature egg with the polar portion of the egg shell already nibbled away.

The egg takes about 5 days to hatch. The young caterpillar emerges by eating away the polar portion of the egg shell. The rest of the egg shell is not eaten by the newly hatched which is about 3mm in length. The dull orange body is reddish laterally and feature a few moderately long setae at its anal end. The head capsule is black in color, and there is a black collar mark on the dorsum of the prothorax.

Two views of a 1st instar caterpillar, early in this stage, length: 3mm.

The newly hatched makes its way to the leaf edge to construct its very first leaf shelter. It ventures out of the shelter from time to time to feed on the leaf lamina in the vicinity. As the caterpillar grows, the body assumes a green undertone. After reaching about 5mm in about 3 days, the caterpillar moults to the 2nd instar.

Two views of a 1st instar caterpillar, length: 4.5mm.

Two views of a late 1st instar caterpillar, dormant prior to its moult.

The body of the 2nd instar caterpillar is initially dull orange but becoming more yellowish as it grows in this instar. The lateral reddish coloration also dissipates in the same time frame. There are numerous, obscure and whitish specks carpeting the body surface. The black colar mark on the prothorax is still present but has become obscure. The dark reddish brown head is broadened sideways to two rounded tips at the upper end. This instar lasts about 4 days with the body length reaching about 8mm.

Two views of a 2nd instar caterpillar, early in this stage, length: 4.2mm.

Two views of a 2nd instar caterpillar, length: 5.8mm.

A late 2nd instar caterpillar, dormant prior to its moult, length: 8mm.

The 3rd instar caterpillar closely resembles the 2nd instar caterpillar. The head capsule is still dark reddish brown but broader sideways and with the two raised points more pronounced, resulting in a heart-shaped outline. The whitish/yellowish specks on the body are now more prominent. This instar takes about 5 days to complete with body length reaching about 12mm.

Two views of a 3rd instar caterpillar, early in this stage, length: 7.5mm.

Two views of a 3rd instar caterpillar, length: 12mm.

Two views of a late 3rd instar caterpillar, dormant prior to its moult.

The 4th instar caterpillar is little changed from the 3rd instar. The yellowish green body is covered with numerous, yellowish specks, and there is hardly any hint of a dark collar mark on the prothorax. This instar lasts about 6 days with body length reaching about 21-22mm.

Two views of a 4th instar caterpillar, early in this stage, length: 12.5mm.

Two views of a 4th instar caterpillar, late in this stage, length: 22mm.

Two views of a late 4th instar caterpillar, dormant prior to its moult.

The 5th instar caterpillar has similar body markings as in the 4th instar. The yellow coloration of the body ground colour and that of the numerous specks is more mellow than in the earlier instar. This final instar lasts for about 8-9 days, and the body length reaches up to 33-40mm.

Two views of a 5th instar caterpillar, early in this stage, length: 22mm.

Two views of a 5th instar caterpillar, length:30mm.

On the last day of 5th instar, the body decolorises to an iridescent shade of pink. The caterpillar ceases feeding and remains in its leaf shelter. In it, the pre-pupatory larva prepares for the pupal phase with a series of silk construction work with the main pieces being a silk girdle across the dorsum of its early abdominal segments, and a short and thickened transverse silk band on the substrate at its posterior end. Pupation takes place about 1 day later.

Two views of a 5th instar caterpillar, late in this stage, length:28mm.

Top: A pre-pupa of the Large Snow Flat secured with silk girdle in its shelter. Bottom: The fresh pupa, note the change to cremastral attachment at the posterior end.

The girdled pupa is secured with its cremaster attached to the short transverse band on the substrate. It has a short thorax, a rather long abdomen, a pointed rostrum and two small ear-like appendages at the leading edge of the mesothorax. The body is pale beige brown dotted with numerous brown to reddish brown spots. Unlike other Tagiades spp., the pupa doe snot have white triangular patches on the sides of its body. Length of pupae: 24-25mm.

Two views of a pupa of the Large Snow Flat.

Left: Frontal view of the anterior of a pupa of the Large Snow Flat. Right: Close-up view of the cremastral attachment.

After about 8 days of development, the pupal turns dark as the development within the pupal case comes to an end.  The following day, the adult butterfly emerges from the pupal case.

Two views of a mature pupa of the Large Snow Flat .

A newly eclosed adult of the Large Snow Flat .

  • [C&P4] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society.
  • Butterflies of Thailand, Pisuth Ek-Amnuay, 2nd Edition, 2012.
  • A Field Guide to the Butterflies of Singapore, Khew S.K., Ink On Paper Communications, 2010.
Text by Horace Tan, Photos by Antonio Giudici, Mark Wong, Federick Ho, Chng CK, Loke PF, Nelson Ong, Sunny Chir, Khew SK and Horace Tan
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Friday, September 27, 2013

Butterflies Galore! : Plain Palm Dart

Butterflies Galore!
The Plain Palm Dart (Cephrenes acalle niasicus)

The Plain Palm Dart is one of two extant species of the genus Cephrenes in Singapore. Males of this species are often confused with the commoner Telicota species which are lookalikes and not easy to identify when in the field. However, the Plain Palm Dart is slightly more unique than the other species in that the females are purple-brown and can be distinguished immediately. The species can be found in urban parks and gardens, and is also quite regularly observed on Pulau Ubin, especially when there are flowering Syzygium trees.

This female Plain Palm Dart was photographed by ButterflyCircle member Loke PF. The butterfly is feeding on the flower of a common "weed", Bidens sp. Females are rarer than males.  The caterpillar of the Plain Palm Dart feeds on the common coconut palm (Cocos nucifera) and one of the "fan" palms (Livistonia sp).  The life history has been recorded here.

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Tuesday, September 24, 2013

Butterflies Galore! : Archduke

Butterflies Galore!
The Archduke (Lexias pardalis dirteana)

The large, robust-bodied butterflies of the genus Lexias are forest-dependent species that seldom stray from the sanctuary of the forested nature reserves of Singapore. They are largely ground feeders, preferring to forage amongst leaf litter and fallen fruits on forest floor. Two of the three extant species of the genus display distinct sexual dimorphism in that the male and female look very different from each other.

This shot, taken by ButterflyCircle member Nelson Ong, shows a male of the Archduke feeding on some liquid nutrients on a tree trunk. The males are velvety black above with a prominent blue marginal border on the hindwing, which continues to the termen of the forewing. The Archduke is a powerful flyer and is usually skittish.

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Saturday, September 21, 2013

Butterfly of the Month - September 2013

Butterfly of the Month - September 2013
The King Crow (Euploea phaenareta castelnaui)

The first week of September saw another unprecedented flood in Singapore - this time on the western side of the island near the National University of Singapore. For the first time, an entire major expressway was completely shut down to all classes of vehicles for about 40 minutes. The Ayer Rajah Expressway, or the AYE was inundated by the sudden downpour in the early morning hours, and coupled with the high tide, caused the flooding of all four lanes.

This 'rainy season' that is known as the South-West monsoon has seen several wet days in September, including weekends, that caused ButterflyCircle members to be cooped indoors (rather unhappily) instead of going out on their regular outings. The 'Sumatras' as these seasonal monsoon winds are called, are forecasted to taper off in October as the inter-monsoon lull will hopefully bring better weather.

For the nature groups, the concerns over the 50km Cross Island MRT line that will start in Changi and end in Jurong will be given a short reprieve as the Land Transport Authority announced that a two-year Environmental Impact Assessment will be conducted to ascertain the impact on biodiversity and the habitats where the line cuts through MacRitchie Nature Reserve. Some initial thought-provoking questions can be found on this site. The NSS also published a position paper on the concerns regarding the initial soil investigation works, as well as the potential ecological damage that the underground tunnelling work may cause during the construction stage.

Dr Wee YC, the author behind the Bird Ecology Study Group, has also penned a series of articles showcasing the biodiversity that may be lost with the Cross Island Line, if it goes ahead as planned. His latest article is posted here. A site to showcase the biodiversity of MacRitchie forest, and to lobby concerned nature enthusiasts and anyone who shares the common cause has been set up. It's called the Love Our MacRitchie Forest site.

Our feature butterfly for the month is the largest species in the genus Euploea often referred to as the 'Crows'. The genus features large distasteful butterflies, usually black or blue, with white spots or stripes on their wings. The King Crow (Euploea phaenareta castelnaui) is the largest member of the genus, with a wingspan between 90-105mm.

The King Crow is a moderately rare species, although it can be regularly observed in local areas, particularly where its caterpillar host plant grows. It is often spotted in the back-mangrove areas of Pasir Ris Park, Pulau Ubin and even in urban areas in the vicinity of its host plant, the Pong Pong Tree (Cerbera odollam).

On the upperside the predominantly dark brownish-black butterfly features a series of violet-tinged apical spots on the forewings. There is a series of white marginal and submarginal spots on both wings. The spots on the underside are smaller although there are some individuals where some of these spots appear violet in colour.

On the upperside of the hindwings, male King Crows feature a raised scent patch in the cell, and there is a certain obvious discolouration at the tornal area of the hindwing. The forewing dorsum of the female is straight, whilst in the males, the forewing dorsum is strongly bowed. Females are typically larger, with a wider wingspan.

The King Crow flies slowly but can be alert and skittish. It tends to fly at higher levels amongst the treetops, stopping occasionally to rest with its wings folded shut. At times, the butterfly is observed to rest with its wings opened flat, as if to sunbathe. It can also be observed feeding on a variety of nectaring plants, and is particularly attracted to the flowers of the Syzygium trees.

The caterpillar host plants were previously planted as a roadside tree and in some housing estates. But in recent years, the tree has fallen out of favour, as the large apple-like fruits have been known to drop and damage parked cars, prompting the authorities to remove the Pong Pong as a roadside tree. It is now more often seen in backmangrove areas and parks, away from carparks.

The complete life history of the King Crow has been recorded in this blog here.  The photo below shows the eclosion sequence of the King Crow.

Text by Khew SK : Photos by Sunny Chir, Khew SK, Loke PF, Bobby Mun, Horace Tan, Tan Ben Jin & Benedict Tay

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