11 October 2009

Life History of Semanga superba deliciosa

Life History of Semanga superba deliciosa

Butterfly Biodata:
Genus: Semanga Distant, 1884
Species: superba H. Druce, 1873

Sub-species: deliciosa Seitz, 1926
Wingspan of Adult Butterfly: 28mm
Caterpillar Local Host Plants:
Mallotus paniculatus (Euphorbiaceae), Melastoma malabathricum (Melastomataceae), Saraca cauliflora (Leguminosae), Macrosolen cochinchinensis (Loranthaceae), Kopsia fruticosa (Apocynaceae), Bridelia tomentosa (Euphorbiaceae), Trema tomentosa (Ulmaceae).

A female Semanga superba resting on a leaf.

The upperside of a female Semanga superba.

Physical Description of Adult Butterfly:
Above, the male is lustrous purple with a black border on the forewing and an orange-red distal border on the hindwing. The female is bluish purple with a wider forewing border. Underneath both sexes are buff-brown with narrow reddish brown post-discal line on the forewing. The hindwing has basal area unmarked, but the tornal half broad and reddish-orange with black spots and metallic blue/green zig-zagged lines. The male possesses two pairs of moderately long filamentous tails at the end of veins 2 and 3, whilst the female features one additional short pair at the end of vein 4.

A female Semanga superba feeding on a leaf in the nature reserve.

A male Semanga superba resting on a perch.

Field Observations of Butterfly Behaviour:
This attractive and small species is infrequently encountered in the nature reserves in Singapore, despite the wide distribution of its many host plants throughout the country. In most encounters, adults are sighted flying rapidly in the vicinity of flowering shrubs and trees. Rare photograph opportunities only arise when they stop to sun-bathe or to take nectar from flowers.

Early Stages:
The immature stages of Semanga superba are polyphagous and so far 7 plants have been recorded as local hosts, with species ID for all but one established. Depending on the host, caterpillars of all instars feed on either young leaves or flower buds.

Host plant: Mallotus paniculatus (also host plant for the Malayan).

Host plant: Kopsia fruticosa. Leaves and flowers.

All field sightings of caterpillars in any instar typically come bundled with a number of ants in attendance. Such strong association with ant species has earlier been observed and documented in a 1995 journal paper by Prof. Fiedler and his colleague. Earlier partial breeding attempts (by Prof. Fiedler, and by Butterflycircle members) were successfuly completed with ants in attendance. Recently, Ben Jin Tan, an active Butterflycircle member, managed to accomplish the task of breeding two specimens from the egg stage to adulthood in total absence of ants, a task previously thought to be impossible. The following account of the complete life history of Semanga superba is based mostly on the growth record maintained and provided by Ben Jin.

A caterpillar of Semanga superba in 5th or 6th instar being attended by ants.

Eggs are laid on the leaf underside or on a perduncle/pedicel of an infloresence The white egg , about 0.9mm in diameter, is shaped like a slightly flattened chinese bun with its surface covered with numerous short spikes and a depressed micropylar sitting atop.

An egg laid on Kopsia fruticosa. Diameter: 0.9mm.
The right panel shows the empty egg shell after hatching.

A cluster of three eggs laid against the midrib on a leaf underside of the Singapore Rhododendron.

Each egg takes about 4 days to hatch. The young caterpillar emerges after nibbling away sufficiently large upper portion of the egg shell. Measured at a length of about 1.2-1.3mm, its pale yellow body is cylindrical in shape, sporting moderately long fine setae running lengthwise, a black head capsule, a large dark prothoracic shield and a light brown to greyish anal plate.

Two views of a newly hatched caterpillar of Semanga superba.

An early instar caterpillar being attended by two ants.

As the caterpillar grows, its body broadens sideway, and red to reddish patches appear on the prothorax, mesothorax and posterior abdominal segments. The growth is slow and after about 4-6 days, it only reaches about 3mm in length when it stops for the moult to the 2nd instar.

Two views of a 1st instar caterpillar, late in this stage.

Covered with numerous short setae, the body of the 2nd instar caterpillar is pale yellow in base color. The prothoracic shield is dark and well developed. The body is onisciform in shape and flattened dorso-ventrally. The three thoracic segments and the first 6 abdominal segments bear a pair of lateral cone-shaped projections furnished with a tuft of long and erect setae. The anal end also features cone-shaped projections with long and erect setae. There are also postmedian series of red markings on the first 6 abdominal segments. The growth in this stage brings the caterpillar to a length of about 4mm, and after about 3 days in this stage, it moults again.

A freshly moulted 2nd instar caterpillar.

Two views of a 2nd instar caterpillar, lengths: 3.8mm.

In the 3rd instar, both the prothoracic shield and the anal plate are black and well developed. The lateral projections all around the body have become rather pronounced. There is also a pair of lateral projections on the 8th abdominal segment which is long and elevated with sclerotized black sheaths housing the eversible and whitish tentacular organs. The dorsal nectary organ on the dorsum of the 7th abdominal segment is clearly discernible. This instar takes 3-4 days to complete with the body length reaching about 7mm before the next moult.

3rd instar caterpillar, early in this stage.

Two views of a 3rd instar caterpillar, length: 5mm.

The 4th instar caterpillar bears few changes from the 3rd instar. One visual difference is the increase in color intensity of the red to reddish brown patches at both ends to dark brown or dark reddish brown. The body base color has also changed to pale green. The postmedian markings on 1st-6th abdominal segments are more prominent with white wavy pink/red/dark-brown strips interminging with white. The dorsal nectary organ is now sitting within a pale reddish-brown patch. The tentacular organs are easily observed as their eversions occur frequently. This instar lasts about 5 days with length reaching 10-11mm.

4th instar caterpillar, early in this stage.

4th instar caterpillars, late in this stage, length: 10mm.

A Semanga superba caterpillar of either 3rd or 4th instar being attended by ants.

The 5th instar caterpillar has broader and more contrasting postmedian series of markings, and the patch containing the dorsal nectary organ is now larger and more prominent. A pair of dark dorsal projections on the mesothorax has also become more elevated. This instar lasts about 6 days with length reaching 13-13.5mm.

A 5th instar caterpillar moving past flower buds of Macrosolen cochinchinensis.

Two views of a 5th instar caterpillar, late in this stage.

The 6th (and final) instar caterpillar has much darker postmedian series of markings. Dark patches of varying sizes appear lateraly with those on the 1st abdominal segment being the largest and most discernible. A mid-sized white to beige dorsal patch also appears on the mesothorax. This instar lasts about 11-12 days with the length reaching about 20mm.

A 5th instar caterpillar feeding on flower buds of Macrosolen cochinchinensis

6th instar caterpillars on Trema tomentosa.

A picture illustrating the differences in the posterior ends of 2nd instar (left) and
6th instar (right). Note the everted tentacular organs.

Towards the end of the 6th instar, the caterpillar ceases eating and chooses a spot on the leaf surface for its pupation site. A pupation shelter is made with multiple silk threads joining opposing leaf surfaces. Within the shelter, the pre-pupatory caterpillar readies itself for pupation by spinning a silk girdle and a silk pad. In the wild, some caterpillars have been found to pupate within ant pavillions.

A pre-pupatory larva of Semanga superba.

Pupation takes place after one day of the pre-pupal stage. The pupa has the typical lycaenid shape, silvery white in base colour with many black patches in greenish tinge on the pupal surface. The pupa has a length of about 10-11mm.

A pupa of Semanga superba within a shallow pupation shelter.

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.

The eclosion sequence of a Semanga superba adult.

  • The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, The Malayan Nature Society.
  • The mature larva and pupa of Semanga superba, Konrad Fiedler and Peter Seufert, Nachr. entomol. Ver. Apollo, N.F. 16 (1): 1-12, 1995.
Text by Horace Tan, Photos by Benedict Tay, Mark Wong, Sunny Chir, Ben Jin Tan and Horace Tan