Life History of the Spotted Black Crow

Life History of the Spotted Black Crow (Euploea crameri  bremeri)

Butterfly Biodata:
Genus: Euploea Fabricius, 1807
Species: crameri Lucas, 1853
Subspecies: bremeri C & R Felder, 1860
Wingspan of Adult Butterfly: 70-90mm
Caterpillar Local Host Plants:  Gymnanthera oblonga (Apocynaceae, common name: Sea Rubber Vine), Parsonsia helicandra (Apocynaceae).

A  Spotted Black Crow  visiting flowers of a Syzygium species in Pasir Ris Park.

Another Spotted Black Crow resting on a tree trunk.

Physical Description of Adult Butterfly:
Above, both sexes are dark brown and feature marginal and submarginal series of white spots. Among the sub-marginal series of spots on the forewing, the spot in space 5 is large and wedge-shaped, while the spot in space 6 is twice as long, and the spots in spaces 7-9 are smaller and lens-shaped. The male does not have a brand above.  Underneath, the wings are brown with marginal and sub-marginal white spots similar to those on the upperside. On the hindwing, there are additional small white spots near the base of spaces 2 to 7.  On the forewing, there are small white spots in spaces 2-4. Both wings have a white spot in the cell.

Field Observations of Butterfly Behaviour:  
The  Spotted Black Crow is relatively uncommon in Singapore. Though not abundant, the adults have been observed in the nature reserves and mangrove habitats in Sungei Buloh Wetland Reserve, Pasir Ris Park and Pulau Ubin. The adults are attracted to flower blooms, and are easiest to approach for photo-taking when they are occupied during their flower visits.  

Early Stages:
The Spotted Black Crow is polyphagous and its two currently known host plants are both in the  Apocynaceae families. The caterpillars feed on leaves and young shoots of the host plants, typically with those in  early instars focusing on  young tender leaves and  those in later instars  on  more mature leaves. The caterpillar has the habit of first cutting the mid-rid or the petiole of a leaf  before eating the leaf lamina beyond the severed point. If the petiole is cut for this purpose, the caterpillar would spin a web of silk threads to secure the severed portion of the leaf.

Local host plant: Gymnanthera oblonga.

The eggs of the Spotted Black Crow are laid singly on the underside of a leaf (typically young leaf) or on the vine of the host plants. The pale creamy yellow eggs are tall standing  (about 1.8mm in height) and somewhat ovoid (diameter: 1mm). The egg surface is covered with  shallow polygonal pits.

Two views of an egg of the Spotted Black Crow.

Two views of a mature egg of the Spotted Black Crow.

Hatching and eating of egg shell by a Spotted Black Crow caterpillar.

The egg takes about 3 days to hatch. The young caterpillar emerges by eating away part of the egg shell. The rest of the egg shell becomes the first meal for the newly hatched, which has a length of about 3mm. The newly hatched has a pale yellowish  body and black legs. The large head capsule is black in color. A pair of very short and inconspicuous dorso-lateral protuberances can be found  on each of the following four segments: 2nd and 3rd thoracic segments, the 2nd and 8th abdominal segments.

Two views of a newly hatched caterpillar, length: 3.2mm.

A 1st instar resting within the marked out zone of a leaf.

Once the newly hatched moves on to feed on the leaf lamina, its body starts to take on a green undertone. The newly hatched has this interesting  habit of marking out a  portion of the leaf with  a series of small bite-marks before eating away the marked out portion. In the final half day of the 1st instar, the body takes on reddish brown transverse stripes on all segments. This instar lasts for 1.5-2 days with the  the body length doubled up to 6 mm.

Two views of a 1st instar caterpillar,  late in this instar, ength: 5mm

The body of the 2nd instar caterpillar has a yellowish orange ground color. From the 2nd thoracic segment to the 8th abdominal segments, there are dark brown  transverse rings interspersed with broad whitish bands. On each of these segments, one broad dark brown transverse is broader than the rest and extending further down to the yellowish orange ventrum ( reaching and passing the spiracles). The most obvious change is the lengthening of the 8 tiny protuberances seen in the 1st instar to short processes, each of which is almost entirely dark brown to black. There are two small black spots on the dorsum of the prothorax, and one large black patch (anal plate) on the posterior end of the body. This instar lasts only 1  day  with the body length reaching about 11.5mm before the moult to the 3rd instar.

Two views of a newly moulted 2nd instar caterpillar, length: 3.2mm

Two views of a 2nd instar caterpillar, length: 9mm

The 3rd instar caterpillar is similar in appearance to the 2nd instar caterpillar. One obvious change is in the 4 pairs of  processes which become proportionately longer. Another change is in the head capsule where two faint whitish lateral streaks have appeared.This instar takes about 1.5 days to complete with body length reaching up to 17mm.

Two views of a newly moulted 3rd instar caterpillar.

Two views of a 3rd instar caterpillar, length: 13mm.

Compared to the 3rd instar, the 4th instar caterpillar has proportionately longer processes.   The black head capsule features two   oblique and joined white stripes and  an outer peripheral white ring. On some specimens, the white stripes on the dorsum take on a pale creamy white coloration. This instar lasts 2 to 2.5 days with the body length reaching about 30mm.

Two views of a 4th instar caterpillar, early in this stage,  length: 18mm.

Two views of a 4th instar caterpillar, length: 27mm

The 5th instar caterpillar again has proportionately longer processes. Otherwise it is rather similar to appearance to the 4th instar caterpillar. On the upper half of the body segment the black stripes are now interspersed with pale creamy yellow bands.

A newly moulted 5th instar caterpillar eating its exuvia on a vine of Gymnanthera oblonga.

As is the case of the Striped Blue Crow, the Spotted Black Crow caterpillar does not have the prosternal gland previously discovered  in caterpillars of  the Blue Spotted Crow (E. midamus singapura) and the King Crow (E. phaenareta castelnaui). When the caterpillar was  intentionally agitated, it would adopt a rather common head-tugged defensive stance.

Two views of a 5th instar caterpillar, length: 36mm.

Two views of a 5th instar caterpillar, late in this instar, length: 45mm.

A Spotted Black Crow going through the chores of becoming a hanging pre-pupa.

The 5th instar lasts for 3.5-4 days, and the body length reaches up to 51-53mm. On the last day, the caterpillar ceases feeding, and its body becomes shortened and decolorised slightly. For pupation, the caterpillar typically chooses a spot on the mid-rib of a leaf underside. At this pupation site, the caterpillar spins a silk pad from which it then hangs vertically to take on the pre-pupatory pose.

A pre-pupatory larva of the Spotted Black Crow.

Pupation takes place 0.5 days after the caterpillar assumes the hanging posture. The pupa  suspends itself from the silk pad with no supporting silk girdle. Initially, the pupa is in a light shade of yellowish brown, but the surface gradually takes on a silvery metalic glitter about a day later. The pupa is rather rotund, and has rows of small dorso-lateral black spots in the abdomen, and three large black spots in the wing pad. Length of pupae: 19-21mm.

A Spotted Black Crow caterpillar moults to its pupal stage.

Three views of a fresh pupa of the Spotted Black Crow, 3-4 hours after pupation.

Three views of a shining pupa of the Spotted Black Crow, one day  after pupation.

Three views of a mature pupa of the Spotted Black Crow, night before eclosion.

After about 7 days of development, the pupal turns black as the development within the pupal case comes to an end. The white spots on the forewing upperside become discernible through the now translucent skin. In the following morning, the adult butterfly emerges from the pupal case, and  perches nearby to expand and dry its wings before taking its first flight.

A Spotted Black Crow emerges from its pupal case.

A newly eclosed male Spotted Black Crow drying its wings on its pupal case.

References:

• [C&P4] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, The Malayan Nature Society.
• The Life Histories of Euploea crameri bremeri and Idea hypermnestra linteata, L.G. Kirton, Tan M.W. and C.G. Kirton, Malayan Nature Journal, 36: 29-43 (1982).
• Butterflies of Thailand, Pisuth Ek-Amnuay, 1st Edition, 2006
• A Field Guide to the Butterflies of Singapore, Khew S K, Ink on Paper Comm. Pte. Ltd, 2010.

Text by Horace Tan, Photos by James Chia, Jonathan Soong, Federick Ho,  Sunny Chir  and Horace Tan

Random Gallery - The Green Baron

Random Butterfly Gallery
The Green Baron (Euthalia adonia pinwilli)

This week's random butterfly is the Green Baron (Euthalia adonia pinwilli).  This male was photographed feeding on the ripening fruit of Melastoma sp. by ButterflyCircle member, Koh CH.  The Green Baron is not rare, and is widely distributed across the island.  It is often observed in urban parks and gardens in locations where its caterpillar host plant, the parasitic Dendrophthoe pentandra is found.  Both males and females are attracted to fermenting fruits.

Butterfly of the Month - April 2012

Butterfly of the Month - April 2012
The Chocolate Grass Yellow (Eurema sari sodalis)

All too soon, the fourth month of 2012 will be over.  In a few days, we will be looking towards the month of May, and most of the working population of Singapore look eagerly forward in anticipation of the public holiday on 1 May, which is Labour Day.  The wet weather from last month has not yet changed much, and Singapore has been receiving above average rainfall in April according to the meteorological information from the National Environment Agency in Singapore.  

On the work front, a momentous event happened just around 8:30pm last evening.  The company that I work for, officially changed hands from the Australians to the Chinese. At a rather quiet and private event between the two parties a small group of 10 of us partook in the little ceremony that will change the lives of my fellow employees and our future outlook.  After 7 years of 'colonialist rule', this Singapore company moves back into the hands of an Asian owner.  Hopefully, it will mean better prospects for all our staff.

The world acknowledges that Asia, and in particular China, will be the engine of economic growth in the coming years.  There will be much to do in this region, and a whole spectrum of challenges to face.  The global economy is swinging more like a rapid-beat metronome rather than a slow pendulum.  Changes will come fast and furious, and businesses have to be agile on their feet to face daily trials.  

As spring makes its way towards summer in the Northern hemisphere, flowers awaken from their cold slumber and add colour to the world of nature.  This flower of the month for April is traditionally accepted to be the Daisy (Bellis perennis).  The Daisy is actually an herb which symbolizes innocence, stability, sympathy, youth and cheerfulness.  In certain cultures the flower also signifies departure and goodbye  (a rather apt symbolism for the current situation at my workplace).  The common colour of the flower is typically white or yellow, but there are hybrids that comes in various colours and shades in between.  

This month, we feature another butterfly with the word "Chocolate" in its common name, after our March's feature butterfly.   Another Pierid, this month's Butterfly of the Month is the Chocolate Grass Yellow (Eurema sari sodalis).  One of six members of the genus Eurema, this small and usually actively flying yellow butterfly is relatively common in Singapore.  Like the other members of its genus, it can be seasonally common.

The Chocolate Grass Yellow's distinct dark brown apex on the forewing beneath instantly sets it apart from its closely-related cousins.  The upperside of the species is a bright lemon yellow with black marginal borders on both the fore and hindwings.  

Another characteristic feature that distinguishes it from the other species amongst the Grass Yellows is the single cell spot on the underside of the forewing.  Earlier articles on this blog describe the key features of the Eurema species in Singapore.  

The Chocolate Grass Yellow is quite common, and is widespread in distribution across Singapore.  It can be found deep in the nature reserves as well as in urban parks and gardens.  Like the other Grass Yellow species, it usually flies restlessly and erratically in search of food.  Photographing this species can be quite challenging at it is active and skittish.

Males of the Chocolate Grass Yellow are regularly observed puddling at damp sandbanks near streams, and muddy forest footpaths.  When puddling they can remain distracted and allow an observer to approach them for a closer look.  Watch closely at the puddling butterfly when the opportunity presents itself, and observe how it excretes fluids whilst it feeds.  This videoclip below, taken by ButterflyCircle member Loke PF, shows the process of feeding and excreting in a Chocolate Grass Yellow.



The female Chocolate Grass Yellow is typically rarer and may be found feeding at flowering plants.  On the upperside, females have broader black marginal borders where the hindwing border is thicker and inwardly diffuse.  The wings of the females are usually also more rounded when compared to the males. 

The species is a fair-weather butterfly, and normally encountered on bright sunny days rather than on overcast days.   The species can be seasonally common and a number of individuals may be encountered puddling at the same spot.  It is always amazing to see so many individuals of the same species feeding together, and then taking off in a cloud of yellow as one approaches them.  

So we bid farewell to the month of April 2012, and look forward to the remaining eight months of the year as we move closer towards the prophetic 12 Dec 2012 with curiousity and for some, even with a bit of trepidation.  For the rest of us, however, life goes on..

Text by Khew SK : Video by Loke PF : Photos by James Chia, Sunny Chir, Goh LC, Federick Ho, Khew SK, Koh CH, Lim WY & Benjamin Yam

Random Gallery - The Brown Awl

Random Butterfly Gallery
The Brown Awl (Badamia exclamationis)

This week's random butterfly was a newly-eclosed individual of the Brown Awl (Badamia exclamationis) shot by veteran ButterflyCircle member, Sunny Chir.  His excellent shot of the Brown Awl on a colourful flower won him various accolades in nature and photography online websites including Image of the Week at NatureScapes.Net and Photo of the Month at Nature Photographic Society Singapore. 

A Trio of Rarities

A Trio of Rarities
Recent Observations of Rare Butterfly Species

The months of March and April 2012 experienced rather unpredictable weather patterns with abnormally heavy rains inundating various parts of Singapore on many days of the months, and then alternating with hot sunny and humid days. These months usually coincide with the beginning of the butterfly season in SouthEast Asia, and generally where more butterflies are sighted, and in larger numbers.

However, the heavy monsoon rains may have somewhat dampened the local butterfly season. It was therefore surprising that ButterflyCircle members managed to encounter three species that are classified "Very Rare" in the 2010 "A Field Guide to the Butterflies of Singapore" book.

#1 : The White Tipped Baron (Euthalia merta merta)

The first encounter was by ButterflyCircle member Federick Ho. He was on his weekend butterfly photography outing on 17 Mar 2012 at Upper Peirce Reservoir Park. He was exploring the usual tracks in the forested areas of the nature reserves when he spotted something unusual. The puddling butterfly was foraging amongst some leaf litter on the forest floor.

Upon closer examination, and after taking shots of the upper and under sides of the butterfly, it was identified as a White Tipped Baron (Euthalia merta merta). This rare Nymphalinae, particularly the female of this species, was last seen by ButterflyCircle members on 31 Jul 2005! It was then recorded as the 286th species in the Singapore Butterfly Checklist.

It was a good record of this very rare forest species after nearly seven years! It is also great that we know that this species continues to thrive and survive in our forests although very rarely spotted. The males of the White Tipped Baron resembles the Malay Baron and the Baron, and has also been seen infrequently, but this is only the 2nd observation of the female after a long absence.

#2 : The Banded Royal (Rachana jalindra burbona)

The 2nd rarity to be observed was on the afternoon of 3 April 2012. Teenaged ButterflyCircle member Jerome Chua decided to take a venture into the nearby forested area near his home to photograph butterflies after school. However, the butterfly activity was low, he left and was heading home along the edge of the forests, when he spotted a butterfly that he had not seen before.

The butterfly was moderately docile, but wary and skittish of movements around it. After spending nearly an hour tracking and allowing the butterfly to be used to his presence, Jerome managed to take a few shots of the butterfly. It turned out to be a pristine specimen of the very rare Banded Royal (Rachana jalindra burbona).

A field shot of this species was first photographed by ButterflyCircle Janet Hong back on 15 Jan 2006 and recorded as species #272 on the Singapore checklist. There were several subsequent encounters of this species in various areas close to the Central Catchment Area. However, the butterfly is still rare and skittish, and not often encountered.

#3 : The Malayan Crow (Euploea camaralzeman malayica)

The last of the trio of rarities encountered in the past two months, is the large and black Malayan Crow (Euploea camaralzeman malayica). This Crow is described to be the 2nd largest of the genus in Malaysia and Singapore after the King Crow. It is very rare, and the first confirmed encounter of this species was a female voucher specimen taken near Upper Peirce Reservoir Park on 22 Feb 1998, during an NParks biodiversity survey. It was feeding at the flowers of a Syzygium tree.

Hence it has been over fourteen years since the last reliable observation of this very rare species was made. This recent observation was in the forests of the Dairy Farm Nature Park, where this male was seen resting on a leaf in the shade, just after 10am. It took off quickly as I approached it for a closer look. Repeated searches of the area on subsequent days were in vain, as the species was not seen again.

It is always a wonder, how rare species appear in the most unexpected places, then disappear for years before the next individual is seen again. Are the forested areas in Singapore large enough for them to hide for so long? Or are they migratory, and appear seasonally? Or perhaps the people who encounter them were just fortunate to be at the right place at the right time?

We'll never know for sure. But that's what makes butterfly-watching interesting and full of surprises. Who knows, just round the corner, at the next flowering bush, is a butterfly species that is new to Singapore, waiting to be discovered!

Text by Khew SK : Photos by Sunny Chir, Jerome Chua, Federick Ho, Janet Hong & Khew SK