Life History of the Great Imperial

An update version of the life history of the Great Imperial can be viewed by clicking this link.

Butterfly Biodata :

Genus : Jacoona Distant, 1884

Species : anasuja C&R Felder, 1865

Subspecies : anasuja C&R Felder, 1865

Wingspan of Adult Butterfly : 36mm

Caterpillar Host Plant : Dendropthoe pentandra (Loranthaceae)

Physical Description of Adult Butterfly : The male of the Great Imperial is deep shining blue on the upperside, with a short oblique band running across the black apical border and dorsal blue patch stretching from the base of the forewing to the termen. Females are predominantly brown above, with a white tornal area on the hindwing. The underside is mainly orange, deepening towards the forewing apex, and the post-discal striae are confined to the tornal half of the hindwing. Both sexes possess a pair of white sword-like tails.

Field Observations of Butterfly Behaviour : The Great Imperial has been described as "rather rare in lowland forest". The adult butterfly appears to be a tree-top dweller and occasionally descends to feed or lay eggs. It shares the behaviour of a closely-related species, the Grand Imperial (Neocheritra amrita amrita) and resembles it closely. Where encountered, the butterfly is observed to fly rapidly, and stops to rest with its wings folded upright. Very rarely, it can be seen sunbathing with its wings opened.

Members of ButterflyCircle who have encountered this butterfly in the nature reserves described it as making "a loud buzzing sound" while in flight.

Early Stages :

The spherical egg has short blunt 'spikes' and is creamy yellow in colour. The egg is laid singly on the upper surface of the host plant leaf. The colour of the eggshell remains unchanged until the caterpillar hatches. After about 3~4 days, the caterpillar hatches from the egg and immediately eats its eggshell as its first meal, until the eggshell is completely consumed.

The newly hatched caterpillar eats its eggshell as its first meal

The 1st instar caterpillar has two reddish brown patches on each side of the abdomen with many fine setae on the body. It usually feeds on the top surface of the leaf, scraping the upper surface lamina and leaving many small crater-like circles on the leaf.

As it moults into the 2nd instar, the caterpillar has more reddish brown patches and leaves with fewer fine setae. At this stage saw-tooth spikes appear along the back of the caterpillar. The caterpillar keeps on the underside and feeds on the lower lamina. The caterpillar grows to slightly over 5mm in length.

2nd instar caterpillar of the Great Imperial

The 3rd instar caterpillar is reddish brown in colour with very few fine setae but has three big prominent "spikes" on its back. It feeds on the edge of the leaves and occasionally on the underside of the leaves as well. It measures about 9mm at the early 3rd instar.

The caterpillar camouflages itself very well, being of a similar colour as its host plant leaves.

The 4th instar caterpillar has a pointed shaped head and is earth brown in colour with 9 reddish brown spiracles, one on the thorax and the rest on the abdominal segments. The 1st spiracle near the head of the caterpillar is set further apart from the rest of the 8 spiracles.

Eighteen days after hatching, the caterpillar measures about 26mm in length.

The 5th and final instar caterpillar measures about 32~36mm in length and is mottled with reddish brown with creamy white patches near the tip of the thoracic segments as well as below the three prominent spikes and the other parts of the body as well.

Final instar caterpillar. Inset : Head shot of the caterpillar.

After a total of 27 days upon hatching from its egg, the caterpillar assumes its pre-pupation pose and remains dormant for about a day. The caterpillar prepares for pupation by attaching itself well by the cremaster without silk pad on the surface of a twig, but unlike many other species, it has no girdle to support the pupa.


The prominent protuberance at the thoracic segement at the pre-pupation stage

Anterior view of the final instar caterpillar

The pupa, attached only by its cremaster bears two prominent paired protuberances. It is grey brown in colour with a dash of powdery green spread over its body.

Thirty-four days after the caterpillar hatched from its egg, the pupa becomes semi-transparent and turns darker, where the wings of the butterfly within are discernible, whilst the abdominal segments turn a light pinkish brown.

Eclosion of the butterfly took place in the afternoon as this beautiful male specimen of the Great Imperial emerged.

A fleshly emerged male Great Imperial holding onto its empty pupa case

Text by Tan BJ ; Edited by Khew SK ; Photos by Tan BJ & Horace Tan

Butterfly Photography at Our Local Parks

Butterfly Watching & Photography at Local Parks
Featuring : Toa Payoh Town Park

Occupying an area of about 4.8 hectares, Toa Payoh Town Park (TPTP) is situated opposite the HDB Hub and the Toa Payoh Bus Interchange, bounded by the Pan-island Express Way, Lor 6 and Lor 2 Toa Payoh. The entrances to the park are located along Lor 6 and Lor 2.

Butterfly activities are usually sighted on the section of the park towards the Lor 2 direction. Here are the popular spots for watching and shooting butterflies at TPTP.

Ixora bushes (probably javanica) below the pedestrian overhead bridge connecting the park and the bus interchange (adjacent to Lor 6) is a must-visit spot, especially when the flowers are in full bloom.

On a sunny morning, you could be thrilled and entertained by many fluttering butterflies such as the Common Mime, Common Grass Yellow, different skippers such as the Palm Bob and the Grass Demon zipping past you at high speeds, or the sun-bathing male Peacock Royal showing off his spectacular upper sides, or the impeccable gliding and sailing in the air demonstrated by the Short Banded Sailor.

A beautiful hairstreak butterfly, the Peacock Royal must be the ‘gem” of the park. The desire of getting good and nice shots of this elegant and relatively rare flying gem always entices many macro photography enthusiasts to visit the park. On a sunny morning when this species is in season , you would see at least a couple of them feeding and staying quite tame on the Ixora flowers.

Other species such as the Common Palmfly, Chocolate Pansy, the Autumn Leaf and Slate Flash are regular visitors to the park.

The Ixora flowers also attract some surprise visitors such as the Green Baron, Plain Banded Awl and the Common Bluebottle at times.

Look out for the tower at the park which stands tall opposite the pedestrian overhead bridge. You will never fail to spot the Common Grass Yellow, a permanent resident in the park, fluttering around the attractive Peacock Flower (Caesalpinia pulcherrima) flowers in front of the tower.

Usually on a sunny day before noon, you could also spot other common species such as Lemon Emigrant and Lime Butterfly. These butterflies are usually skittish and alert but when they decide to feed on the nectar of the flowers, you can nail them quite easily.

A prominent sheltered open space near the Lor 2 entrance that you will not miss is the multi-function pavilion. Strolling leisurely on the boardwalk next to the pavilion, you will be charmed by the pink and red flowers of the Jatropha shrubs and the purple Cat’s Whiskers on both sides of the boardwalk. If you are observant, you are likely to sight some small butterflies such as the Lesser Grass Blue, Pale Grass Blue, Pygmy Grass Blue or Ciliate Blue fluttering and feeding on these flowers.

If you visit the park early in the morning, chances are good that you would find some butterflies resting in the comfort of the morning cool. They are so tame and lethargic that you can set up a tripod or monopod to get your perfect shots at your own time.Sometimes you may be able to spot a large colony of Tailless Line Blue congregating around the yellow Dieffenbachia bushes along the jogging path next to the boardwalk.

Last but not least, look out for butterflies puddling on the damp soil or in front of the toilet. The picture below shows a male Striped Albatross getting “drunk” in front of the toilet.

TPTP is a convenient neighbourhood park that offers everyone good opportunities to watch, appreciate and take pictures of many beautiful butterflies. ButterflyCircle members have sighted and recorded over 30 species of butterflies at the park.

So next time when you visit the park, spend a bit more time at the favourite spots to observe and enjoy these “flying jewels” in action.

Text by Federick Ho ; Edited by Khew SK ; Photos by Federick Ho, Khew SK, Simon Sng, Sum CM, Sunny Chir and Tan BJ

Toa Payoh Town Park Map

The Toa Payoh Town Park is one of about 300 parks in Singapore which is designed and managed by the National Parks Board (NParks). As the custodian of Singapore's world-renown lush greenery, NParks maintains and enhances public green spaces which includes parks, gardens, green connectors and nature reserves, all of which are part of Singapore's aspirations of being a City in a Garden.

Life History of the Green Oakblue

Butterfly Biodata :
Genus : Arhopala Boisduval, 1832
Species : eumolphus Cramer, 1780
Subspecies : maxwelli Distant, 1885
Wingspan of Adult Butterfly : 45mm

Caterpillar Host Plant : to be identified.

Adult male Green Oakblue




Adult female Green Oakblue

Physical Description of Adult Butterfly : On the underside, the adult butterflies have the post-discal spot in space 4 of the forewing moved out of line with the spots above and below it; and on the hindwing the post-discal spot in space 6 is below the spot in space 7. The adults are tailed and moderately large. The male has a brassy green upperside with the forewing border decreasing in thickness from the tornus to the apex. In contrast, the female has a purple blue upperside, and on the forewing the border usually reaches the apex of the cell.

Field Observations of Butterfly Behaviour : This species is a forest denizen and the adult butterflies have been observed to fly in the vicinity of its host plant within the nature reserve areas of Singapore. Both sexes spend much time resting among foliage on the uppersides of leaves with wings closed. When disturbed they usually take off with a swift flight. In sunny weather, they can be spotted sunbathing on uppersides of leaves with both wings opened flat. This sunbathing behaviour has been observed to be a well-timed event taking place in the afternoon.

Early Stages :

The female oviposits on the underside of a mature leaf of the host plant. Each time a single egg is laid, but as the mature leaf is rather large, sometimes several eggs can be found (singly, not in a cluster) on the same leaf. The egg is small (about 0.5mm in diameter) and white in colour, circular with a slightly depressed micropylar area and a reticulated pattern of intersecting ridges.


Female Green Oakblue with abdomen curved to lay egg on the leaf underside.


Left : Fertile egg of the Green Oakblue ; Right : and Empty egg shell --- partially eaten

After about 2 days, the caterpillar hatches from the egg. As it makes its way out of the egg shell, the tiny young larva consumes the eggshell partially for its exit. As the caterpillar of all instars only eats the soft young leaves of the hostplant, the newly hatched has to move away from the mature leaf (where the egg was laid), and make its way to the younger leaves of the host plant. Upon arrival at the young leaves, the caterpillar nibbles away on the leaf surface, making tiny holes on the leaf and leaving a trail of frass behind it.


Left : The large (up to 30cm in length) and hardened mature leaves of the host plant where eggs are laid on the undersides by the female Green Oakblue. ; Right : Young shoot of host plant with soft leaves for caterpillars of Green Oakblue to chew on.

The caterpillars of all instars have a much flattened appearance and have a large, flattened, semicircular first thoracic segment . They construct loose leaf shelters to which they return for rest and for hiding when their feeding activity nearby is disturbed. Typically the caterpillars of all instars would rest next to the main rib of the growing leaf. The caterpillars also have a dorsal nectary organ and have been observed to be attended by ants of two species. On one site, the attending ants are of the Polyrachis species, but on another site, the attending ants are much smaller and species ID of which is yet to be determined. The Green Oakblue larvae have also been observed to be victimized by a parasitoid of Apanteles sp.

A 4th instar caterpillar being attended to by an ant of Polyrachis sp.

The 1st instar caterpillar is initially light yellowish with a tinge of beige. As it grows, it loses the beige tinge and becomes increasingly yellowish. It starts at about 1mm in length, and grows to about 3mm in 2 days before the moult to the 2nd instar.

The 2nd instar caterpillar is distinctly yellow in color and has a prominent whitish dorsal marking.

The 3rd instar caterpillar has a similar appearance to the 2nd instar caterpillar. Because of its larger size, the body markings are now more prominent. An ``hour-glass’’ mark on the anal segment is also visible now.

1st instar caterpillar on the young leaf next to the evidence of its feasting.

2nd instar caterpillar . More yellowish, more distinct dorsal marking.

3rd instar caterpillar showing more prominent body markings and the ``hour-glass’’ mark on the anal segment.

The 4th instar caterpillar is essentially similarly patterned as the 3rd instar, but it now takes on a light greenish and somewhat translucent appearance. The dorsal markings become distinctively fluorescent yellow in contrast..

4th instar caterpillar in its shallow leaf shelter

The 5th and final instar caterpillar is much bigger with increases in both body length and width. The ``hour-glass’’ mark on the anal segment is longer visible. Initially the caterpillar has a greenish colouration but slowly this gives way to a yellowish colouration as it matures and grows to a length of about 20-22mm.

Two 5th instar caterpillars, with the green one being earlier in growth.


An ill-fated 5th instar caterpillar with cocoons of a Apanteles sp. underneath it. The poor caterpillar eventually died hours later.

About 16 days after its hatching from the egg, the caterpillar ceases its feeding activity and its body color becomes reddish brown. At the same time its body length gradually becomes shorter. This lasts for about one day. The caterpillar then goes into a one and half day of pre-pupation pose within a loose leaf shelter. During this time, the caterpillar prepares for pupation by spinning a silk girdle and a silk pad to which it attaches itself via cremastral hooks.


The late 5th instar caterpillar is reddish brown and shrunk in length a day before pre-pupation.


The preparatory caterpillar hours before pupation. The silk girdle is already constructed.

The pupa has a shape typical of any lycaenid species, and a length of 14-16mm. It is light brown with a short dorsal stripe, and has a somewhat produced anal segment.

After about 10 days, the pupal shell turns transparent and the wings of the soon-to-be-emerging butterfly can be seen through the pupal shell. Eclosion takes place within the next 24 hours, typically one or two hours after dawn.


Two views of a pupa of the Green Oakblue.


All ready for eclosion. The upperside wing pattern of the adult butterfly can be seen through the now transparent pupal case.

An adult male Green Oakblue

Text by Horace Tan ; Photos by Horace Tan, Sunny Chir & Khew SK