19 December 2015

Life History of the Spotted Judy

Life History of the Spotted Judy (Abisara geza niya)

Butterfly Biodata:
Genus: Abisara C. & R. Felder, 1860
Species: geza Fruhstorfer, 1904
Subspecies: niya Fruhstorfer, 1914
Wingspan of Adult Butterfly: 36-46mm
Caterpillar Local Host Plants: Embelia ribes (Myrsinaceae), Embelia canescens (Myrsinaceae).

Physical Description of Adult Butterfly:
Both sexes have their hindwings prominently angled at vein 4. On the upperside, the male is deep crimson brown with a pale, whitish and diffuse subapical band on the forewing and black submarginal spots in spaces 4, 5, and 1b on the hindwing. The female is paler and marked similarly but with its forewing subapical band much broader, and there are two diffuse whitish postdical bands on each wing. On the underside, both sexes are paler and each wing has a pair of diffuse, pale-purplish, postdiscal bands. The outer band on the hindwing has a series of black, white-edged, submarginal spots in spaces 1b, 4, 5 and 6. The female has broader and paler transverse bands. The hindwing discal band is dislocated at vein 4.

Field Observations of Butterfly Behaviour:
The adults are moderately rare and are typically sighted in the forest understorey within nature reserves and in a hill park. The timid and skittish adults are often seen perching on leaves with half open wings, turning and hopping from one perch to the next.

Early Stages:
The local host plants known to date are both Emelia species. One of them, Emelia ribes, is more widespread and can also be found in hill parks and wastelands. The immature stages of the Spotted Judy feed on leaves of the host plant. In the first two instars, the caterpillar feeds by grazing on the leaf surface while in the later instars, it feeds by chomping away at the leaf edges. Between feeds, the caterpillars of all instars rest on the leaf underside.

Local host plant #1: Embelia canescens.

Local host plant #2: Embelia ribes.

A mating pair of the Spotted Judy.

Each egg is laid singly on the underside of a leaf on the host plant, typically close to the leaf edge. Each egg is lime green, somewhat conical in shape with a diameter of about 0.7mm. The egg surface is generally smooth and there is a mid-level belt of fine hairs encircling the egg.

Two views of an egg of the Spotted Judy.

Two views of a mature egg of the Spotted Judy.

It takes about 3.5-4 days for the egg to hatch. The young caterpillar consumes part of the egg shell to emerge. With a length of about 1.6-1.9mm, it has a greyish white body which is greenish on the dorsum of anterior segments. The colour of the head follows that of the body. There are moderately long black dorso-lateral setae and exceptionally long whitish sub-spiracular setae. The body color changes to pale yellow with a green undertone as it feeds and grows.

A newly hatched caterpillar resting next to its egg shell.

Two views of a 1st instar caterpillar, length: 2.8mm.

The first instar lasts about 4-5 days and the body length reaches about 3.5mm. Prior to the moult to 2nd instar, the body shortens and takes on a pumped up appearance. This shortening routine also occurs prior to all subsequent moults.

Two views of a late 1st instar caterpillar, dormant prior to its moult, length: 3.3mm.

The body color of the 2nd instar caterpillar is pale yellow with a greenish undertone. Overall, the appearance is little changed from the 1st instar. This instar lasts for about 4-5 days and the caterpillar grows to a length of about 6-6.3mm before the moult to the 3rd instar.

Two views of a 2nd instar caterpillar, newly moulted.

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

Two views of a late 2nd instar caterpillar, dormant prior to its moult, length: 5.8mm.

The 3rd instar caterpillar is still yellowish green but with green dominating. Closer scrutiny reveals that the body surface is marked with numerous tiny whitish speacks. The dorso-lateral setae are black in colour while the sub-spiracular setae are still whitish. After 4-5 days in this stage with the body length reaching a maximum of about 10.5-11mm, the caterpillar moults to the 4th and final instar.

Two views of a 3rd instar caterpillar, early in this stage, length: 6.5mm.

Two views of a 3rd instar caterpillar, length: 10.8mm.

Two views of a late 3rd instar caterpillar, dormant prior to its moult, length: 10.5mm.

A late instar caterpillar of the Spotted Judy found in the field.

The 4th instar caterpillar resembles the 3rd instar caterpillar closely but with much greater number of tiny whitish specks on the body surface. The body and the head are both yellowish green in color.

Two views of a 4th instar caterpillar, early in this stage, length: 11.8mm.

Two views of a 4th instar caterpillar, length: 20.5mm.

The 4th instar lasts for about 7-8 days and the body grows up to a length of about 24-28mm. On the last day of this final instar, the caterpillar ceases food intake and its body shrinks in length. It then finds a spot on the leaf underside where it spins a silk pad and a silk girdle to secure itself for the pupation event.

Two views of a pre-pupatory larva of the Spotted Judy

Pupation takes place after 1 day of the pre-pupal period. The greenish pupa has a diamond-shaped outline, being broader at mid-body, less so at the anterior end, and rather pointed at the posterior end. The green body surface is marked with numerous paler and more yellowish specks. Laterally, there are whitish setae running along the fringe of the body. Each pupa is about 16-19mm in length.

Two views of a pupa of the Spotted Judy.

Six to seven 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.

Two views of the mature pupa of  the Spotted Judy.

A newly eclosed Spotted Judy expanding its wings near its pupal case.

  • [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, 2nd Edition, 2015.
Text by Horace Tan, Photos by C K Chng, Nelson Ong, Frederick Ho, C J Huang, Sunny Chir, Khew SK and Horace Tan

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