30 March 2013

Life History of the Malay Tailed Judy

Life History of the Malay Tailed Judy (Abisara savitri savitri)

Butterfly Biodata:
Genus: Abisara C. & R. Felder, 1860
Species: savitri C. & R. Felder, 1860
Subspecies: savitri C. & R. Felder, 1860
Wingspan of Adult Butterfly: 40-50mm
Caterpillar Local Host Plants: Embelia ribes (Myrsinaceae), Embelia canescens (Myrsinaceae).

Physical Description of Adult Butterfly:
Above, the wings are rusty brown with two diffuse white transverse stripes on the forewing, the inner one being more sullied and stretching from mid-costa to the dorsum before the tornus. The hindwing has a similar diffuse white postdiscal band. There are two black marginal spots in spaces 4 and 5 on the hindwing separated by an orange bar. A long, white-tipped tail is present at the end of vein 4 on the hindwing. Underneath, the wings are similarly marked as per above but are more distinctly coloured with bright shades of white in the stripes set against a ground colour of yellowish brown. The basal halves of the wings are in a paler shade of yellowish brown.

Field Observations of Butterfly Behaviour:
The adults are moderately rare and are typically sighted in the forested areas of the nature reserves, and in a hill park where its host plant is growing in relative abundance. 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 know to date are both Emelia species growing in the nature reserves. One of them, Emelia ribes, is more widespread and can also be found in various hill parks and wastelands. The immature stages of the Malay Tailed Judy feed on the relatively young 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 ribes.

Local host plant #2: Embelia canescens.

Each egg is laid singly on the underside of a leaf on the host plant, typically close to the leaf edge. Each egg is dark purplish blue, somewhat conical in shape with a diameter of about 0.75-0.8mm. 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 Malay Tailed Judy.

A sequence of three pictures, ordered from left to right, showing the development of an egg over the course of 3 days.

A newly hatched caterpillar, next to its half eaten egg shell.

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 2.0mm, it has a greyish white body with a dorsal green band. The head is greyish white. 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.

Two views of a 1st instar caterpillar, late in this stage, length: 3mm

The first instar lasts for about 3 days and the body length reaches about 3.6mm. Prior to the moult to 2nd instar, the body shortens and takes on a pumped up appearance. This shortening routine also occurs prior to each of the subsequent moults.

Two views of a 1st instar caterpillar, late in this stage, length: 3mm.

The body color of the 2nd instar caterpillar is pale yellow with a greenish undertone. There are numerous very short white setae covering the body surface. The exceptionally long white sub-spiracular setae are still present and a few black setae can be found hidden among the white ones. This instar lasts for albout 3-4 days and the caterpillar grows to a length of about 6mm before the moult to the 3rd instar.

Two views of a 2nd instar caterpillar, length: 4.8mm.

Two views of a 2nd instar caterpillar, late in this stage. length: 5.3mm.

The 3rd instar caterpillar is still yellowish green but with green dominating. Otherwise, it bears a strong resemblance to the 2nd instar caterpillar. Closer scrutiny shows that no black setae are present among the sub-spiracular tuffs of white setae. After 3-4 days in this stage with the body length reaching a maximum of about 9.5-10mm, the caterpillar moults to the 4th (and penultimate) instar.

A newly moulted 3rd instar caterpillar, eating its exuviaa, length: 5.8mm.

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

A 3rd instar caterpillar, dormant prior to its moult, length: 9mm

A Malay Tailed Judy caterpillar moults from the 3rd to the 4th instar.

The 4th instar caterpillar resembles the 3rd instar caterpillar but with a much denser set of sub-spiracular setae. The body is mainly yellowish green in color. The numerous short setae carpeting the body surface are now much shorter and yelow to green in colour. The head, which is colored greyish white in the first three instars, is now pale yellowish green. The 4th instar lasts for about 3.5-5 days and the body grows up to a length of about 16-16.5mm.

A newly moulted 4th instar caterpillar, next to its exuvia, length: 9mm.

Two views of a 4th instar caterpillar, length: 14mm.

A close-up view of the body surface of a 4th instar caterpillar.

A 4th instar caterpillar, dormant prior to its moult, length: 15.5mm.

The 5th instar caterpillar resembles the 4th instar caterpillar closely. The numerous short setae carpeting the body surface are now predominantly green in colour and less conspicuous. Overall the body colour is in a stronger shade of yellowish green to lime green, with the head capsule also taking on a greenish tinge.

A newly moulted 5th instar caterpillar, eating its exuvia, length: 15.2mm.

Two views of a 5th instar caterpillar, length: 26mm.

Two views of a 5th instar caterpillar, length: 29mm.

The 5th instar lasts for about 5-7 days and the body grows up to a length of about 27-29mm. 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 in a head-up manner. As the pre-pupa lays dormant, the development within causes several bluish spots and one black dorsal spot to be visible towards the end of the pre-pupal period.

Two views of a pre-pupatory larva of the Malay Tailed Judy

Pupation takes place after 1-1.5 days 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 body has one prominent black dorsal spot on the 1st abdominal segment and a number of bluish spots, varying from two to eight, on the remaining segments. Laterally, there are lateral wedge-shaped appendages on 3rd-9th abdominal segments. The prothorax also features lateral fin-like appendages. Each pupa is about 21-23mm in length.

A Malay Tailed Judy caterpillar moults to its pupal stage.

Two views of a pupa of the Malay Tailed Judy.

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 a male Malay Tailed Judy.

A newly eclosed Malay Tailed Judy drying 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, 2010.
Text by Horace Tan, Photos by Benjamin Yam, Nelson Ong, Sunny Chir and Horace Tan

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