23 June 2018

Life History of the Banded Yeoman

Life History of the Banded Yeoman (Cirrochroa orissa orissa)

Butterfly Biodata:
Genus: Cirrochroa Doubleday, 1847
Species: orissa C & R Felder, 1861
Sub-species: orissa C & R Felder, 1861
Wingspan of Adult Butterfly: 55-65mm
Caterpillar Local Host Plant: Ryparosa scortechinii (Achariaceae).

Physical Description of Adult Butterfly:
On the upperside, the wings are orchreous brown with a broad yellow post-discal band on the forewing. The apical area beyond the yellow band is dark brown to black. The hindwing has black marginal, submarginal and distal lines, and a series of black post-discal spots. On the underside, the wings are paler orcheous brown than the upperside and the broad discal band in the forewing is whitish. The broad apical area on the forewing has two white apical spots. The hindwing has white marginal, submarginal and distal bands, and the series of small black post-discal spots are embedded in larger orange spots. The female is paler than the male.

Field Observations of Butterfly Behaviour:
The Banded Yeoman is moderately rare in Singapore, and has only been encountered at a few sites in the nature reserves. The adults are rapid in flight and not easy to photograph. Typically, photography opportunities arise when the males are puddling on wet ground, or when the females are taking breaks between oviposition runs. In flight, the Banded Yeoman can be mistaken for the Rustic (Cupha erymanthis lotis), which is the commoner of the two species in Singapore.

Early Stages:
Caterpillars of the Banded Yeoman have been observed to feed mainly on young to middle-aged leaves of the local host plant, Ryparosa scortechinii. This plant is found only at a few sites in the central catchment reserve. The scarcity of this plant confines the occurrence of the Banded Yeoman to the surrounding forested areas.

Local host plant: Ryparosa scortechinii.

A mating pair of the Banded Yeoman.

Eggs of the Banded Yeoman are laid singly or in small groups of 2 to 3 on the leaf underside or young shoots of the host plant. Sometimes eggs can be found laid on the cobweb or other plants in the vicinity.

A female Banded Yeoman laying an egg on the leaf underside of the host plant.

A female Banded Yeoman laying an egg on the stem of a vine in the vicinity of the host plant.

A number of eggs laid on a cobweb spun between stem, petiole and leaf of the host plant.

The whitish egg is somewhat globular in shape and its surface is marked with small rectangular to hexagonal pits. The micropylar sits atop the egg. Each tiny egg has a diameter of about 0.75-0.8mm, and a height of about 0.8-0.85mm.

Two views of an egg of the Banded Yeoman.

Two views of a maturing egg of the Banded Yeoman.

The egg takes about 2.5 to 3 days to hatch. The young caterpillar emerges by eating away part of the egg shell. The rest or part of the remaining egg shell becomes the first meal for the newly hatched which is about 2mm in length. It has a cylindrical and pale pinkish body covered with many small tubercles and long setae. The head capsule is coloured as per the body and has two large black lateral patches.

Two views of a newly hatched caterpillar of the Banded Yeoman, length: 2mm.

The 1st instar caterpillar feeds on the lamina of young leaves and between feeds, it typically rests on leaf underside against the midrib. The body colour takes on a pale yellowish green undertone as it grows. After reaching about 4-4.2mm in 1.5-2 days, the caterpillar moults to the 2nd instar.

Two views of a 1st instar caterpillar, length: 2.6mm.

The body of the 2nd instar caterpillar is yellowish green. Long processes, greyish in colour, run along the length of the body. Each process has a number of fine, black, lateral spines emanating from it. On each side of the body, there are three series of such processes: One series occurs dorso-laterally, another lateraly and the last sub-spiracularly. The head capsule is yellowish with two lateral black patches. This instar lasts about 1-1.5 day with the body length reaching about 6.5mm.

Two views of a newly moulted 2nd instar caterpillar.

Two views of a 2nd instar caterpillar, length: 6mm.

The 3rd instar caterpillar has the dorso-lateral and lateral processes proportionately longer and black in color. The body is yellowish with a green undertone in all segments except for the 3rd to 6th abdominal segments which are dark greenish to brownish. The head capsule is still yellow but now featuring four small, but prominent black patches. This instar takes about 1.5-2 days to complete with body length reaching about 11mm.

Two views of a 3rd instar caterpillar, length: 7mm.

Two views of a 3rd instar caterpillar, length: 9.5mm.

The 4th instar caterpillar closely resembles the 3rd instar caterpillar. It has proportionately longer processes when compared those in the 3rd instar. These processes are mostly white-tipped. Furthermore, the 3rd to 6th abdominal segments are now darker than they were in the 3rd instar, being in dark brown to black. This penultimate nstar lasts about 2 days with the body length reaching about 17mm.

Two views of a newly moulted 4th instar caterpillar.

Two views of a d 4th instar caterpillar, length: 13.5mm.

The 5th (and final) instar caterpillar bears close resemblance to the 4th instar caterpillar. Compared to those in the 4th instar, the white tips of the long processes are proportionately longer and more prominent.

An early 5th instar caterpillar of the Banded Yeoman.

Two views of a 5th instar caterpillar, length: 27mm.

Two 5th instar caterpillars sighted on the leaf underside in the field.

The 5th instar lasts for 3-4 days, and the body length reaches up to 29mm. On the last 0.5 day, the body shortens and decolorizes to pale beige brown in the 3rd to 6th abdominal segments. The caterpillar ceases feeding and wanders around. Eventually it stops at a spot on the underside of a leaf, and spins a silk pad from which it hangs vertically to take on the pre-pupatory pose.

Front view of the head capsule of a 5th instar caterpillar of the Banded Yeoman.

Two views of a pre-pupatory larva of the Banded Yeoman.

Pupation takes place about 0.5 days later. The pupa suspends itself from the silk pad via the cremaster attachment. It is almost entirely white and bears a few small, black patches dorsally. Dorso-laterally, along the body length, there are pairs of long, white, curled processes, one to each segment. Posterior pairs of these processes are orange basally and black below the tip. Length of pupae: 17-19mm.

Two views of a pupa of the Banded Yeoman.

Two views of a mature pupa of the Banded Yeoman.

After about 4 days of development, the pupal skin of the mature pupa turns translucent and the wing upperside become discernible as a result. The eclosion event takes place the next day.

The eclosion event of a Banded Yeoman.

A newly eclosed male Banded Yeoman resting on its pupal case.

  • [C&P4] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society, 1992.
  • Butterflies of Thailand, Pisuth Ek-Amnuay, 2nd Edition, 2012.
  • A Field Guide to the Butterflies of Singapore, Khew S.K., Ink On Paper Communications, 2nd Edition, 2015.
Text by Horace Tan, Photos by L C Goh,  Frederick Ho,  Khew S K and Horace Tan

Special acknowledgement to Craig Williams for identifying the local host plant of the Banded Yeoman as Ryparosa scortechinii.

16 June 2018

BioBlitz Singapore

Bioblitz Singapore
Citizen Science Biodiversity Surveys in Singapore

A group of butterfly watchers checking out some puddling Lycaenids along the Rail Corridor during the BioBlitz survey

A BioBlitz is a field biodiversity survey to record all the living species within a designated area, usually over a short period of time. Groups of trained scientists, naturalists, volunteers and members of the public conduct an intensive field study over a continuous time period - ranging from 24 hours to a week. The public component to many BioBlitzes is to encourage the 'unconverted' to participate in these biodiversity surveys and to cultivate an appreciation and respect for nature.

Boyi, our knowledgeable NParks facilitator for the BioBlitz survey, showing participants a butterfly caterpillar

The term “BioBlitz” was coined by Susan Rudy, a naturalist with the US National Park service, in 1996. A BioBlitz refers to a concerted effort by scientists and the community to record as many species of flora and fauna as possible within a specific location and timeframe. The initiative caught on, and today, BioBlitzes have been conducted around the world, including the United Kingdom, Canada, Australia, Hong Kong, Malaysia and Singapore. Many BioBlitzes are conducted in urban and easily accessible areas to encourage the public to spot and identify the local biodiversity around them, literally in their "own backyards".

In Singapore, the NParks-Community In Nature BioBlitz surveys provide a unique opportunity for the community to learn from taxonomic experts, with the hope that such programmes will encourage stewardship of biodiversity amongst Singaporeans. The first BioBlitz surveys were started in 2016 at Pasir Ris Park and Pulau Ubin and in 2017 at Kent Ridge Park. NParks conducted its first nationwide BioBlitz programme over the course of seven days as part of the annual Biodiversity Week (20 to 28 May 2017). The Nationwide BioBlitz, the first of its kind on such a scale in Singapore, took place across around 90 sites in schools, parks, and gardens from 20 to 26 May 2017.

In 2018, NParks organised a suite of events and activities during Biodiversity Week (18 May to 3 June) to encourage the community to explore and encounter nature in Singapore. These programmes took place in schools, urban parks, gardens and nature areas, and involve partners from schools, research institutions, and nature-interest groups. The Nationwide BioBlitz surveys involved over 3300 citizen scientists surveyed around 80 sites across Singapore, including parks, gardens, nature areas and schools, and also for the first time, covered both terrestrial and marine sites.

Participants of the BioBlitz survey walking along the Rail Corridor

As part of the Nationwide BioBlitz week, which covered biodiversity surveys over no fewer that 33 parks and gardens in Singapore, ButterflyCircle members led a survey over a short stretch of the Rail Corridor starting at the Rail Mall. Concurrently, there were surveys on birds and dragonflies over the same stretch. Our butterfly survey took slightly over 3 hours and we recorded a total of 28 species of butterflies over that short stretch of the Rail Corridor.

Participants of the BioBlitz @ Rail Corridor, waiting for the butterfly and dragonfly surveys to start

After a quick briefing, the group was all set to start the survey!

The BioBlitz survey started at around 8:20am when the group of participants were assembled and all ready to go. Our group of 16, inclusive of 3 BC members and Boyi from NParks, started on the transect in rather cloudy weather and commenced counting all the butterflies that we were able to spot.

Map of our survey trail along the Rail Corridor

The stretch of the Rail Corridor can be considered quite 'green' and rich with biodiversity. The survey trail is immediately adjacent to the Bukit Timah Nature Reserve, which is a good catchment for butterflies and other animals. The trail is flanked on the western boundary by Upper Bukit Timah Road.

A group of participants from the dragonfly survey taking photos of dragonflies along the stream

A small stream alongside the trail provided the humidity and water habitat for other organisms like dragonflies, fishes and frogs. Along the main trail, the botanical diversity in terms of low bushes, wildflowers and host plants provided enough habitats for butterflies to flutter around in search of food.

Some puddling butterflies spotted at the BioBlitz survey

Parts of the footpath were open sandy and damp areas for some butterflies to puddle in search of various chemicals for nutrition and specific physiological and biological functions that they need these active ingredients for. Indeed, the group encountered several species of Lycaenids puddling at certain sandy spots. Several of these species were cooperative enough to even allow handphone shots of them.

A male Chocolate Albatross (this one's shot in Malaysia, where it is common) was spotted during our survey at the Rail Corridor

An interesting sighting was the Chocolate Albatross (Appias lyncida vasava) a seasonal migrant that usually appears during the months of March to May when the species is abundant up north in Malaysia. A male was spotted flying along the survey trail.

Participants looking at the butterfly ID sheets and scorecards

A Gram Blue that was spotted just before the survey started

It was an enjoyable outing, keeping a sharp eye out for butterflies and sharing useful information about butterflies' behaviour, the way they fly, and tips on how to ID them. Members of the public, including young children were enthusiastic and learned fast. Boyi created some visual checklists to help the volunteers ID the common species that can be found in urban parks and gardens.

A dedicated Butterfly Watch programme is also available for those who prefer to just record butterfly sightings in various nature areas in Singapore. The Butterfly Watch is a citizen science initiative, organised by NParks in collaboration with ButterflyCircle, to get Singaporeans involved in collecting valuable information about the butterflies in our parks and gardens.

All sorts of "biodiversity"during the surveys are game for a snapshot

With the data collected from many survey transects from the various parks around Singapore, the information will contribute towards better park management and conservation measures. So if you're passionate about nature and butterfly watching, do look out for the announcements on the NParks' Community In Nature initiatives like BioBlitz and Butterfly Watch and contribute to the conservation and protection of our natural heritage in Singapore!

Group shots of the Bird, Butterfly and Dragonfly BioBlitz teams at the Rail Corridor

Text by Khew SK and Zhou Boyi ; Photos by Huang CJ, Khew SK and Zhou Boyi.