31 January 2015

Life History of the Common Four Ring

Life History of the Common Four Ring (Ypthima huebneri )


Butterfly Biodata:
Genus: Ypthima Hübner, 1818
Species: huebneri Kerby, 1871
Wingspan of Adult Butterfly: 30-35mm
Caterpillar Local Host Plant: Ottochloa nodosa (Poaceae).




Physical Description of Adult Butterfly:
The adults are typically small as compared to other Ypthima spp. present in Singapore. On the upperside, the wings are greyish brown with a moderately large, bi-pupilled, yellow-ringed, subapical ocellus on the forewing, and two yellow-ringed ocelli in spaces 1b and 2 on the hindwing. The male has a greyish black  sex brand in the distal area of the forewing. On the underside, both wings are pale greyish to bluff brown and are traversed by numerous fine dark brown striae. The forewing has a large, bi-pupilled, yellow-ringed, subapical ocellus. The hindwing has four yellow-ringed ocelli in spaces 1b, 2, 3 and 6 with the one in space 1b bi-pupilled.

A sun-bathing male Common Four Ring showing its upperside.

A sun-bathing female Common Four Ring showing its upperside.


Field Observations of Butterfly Behaviour:
The Common Four Ring is moderately common in Singapore, and is mostly sighted in localized areas within the nature reserve. Adults are usually observed flying low among vegetation in and around grassy patches on open areas. As with other Satyrinae members, the adults have a feeble flight. They typically fly in an erratic and jerky manner as their wings are closed for a relatively long period during flights. In sunny conditions, the adults have the tendency to sun-bath with fully open wings.






Early Stages:
Only one local host plant, a common grass species, Ottochloa nodosa, has been recorded so far. It is believed that other grass spp. could also be utilized by the Common Four Ring as its larval host plant. The caterpillars feed on leaves of the host plant, and have been observed to forcefully ejecting their frass pellets, a larval habit rarely seen outside the skipper/flat families.

Host plant: Ottochloa nodosa.

A mating pair of Common Four Ring.

The eggs are laid singly on the leaf blade or the stem of its host plant, or on other plants or objects in close proximity to the host plant. Each egg is globular in shape (about 0.9mm in diameter) and bluish green in colour. The egg surface is covered with many small polygonal patches.

Two views of an egg of the Common Four Ring laid on the underside of a leaf of dicot plant.

Two views of a mature egg with the head vaguely distinguishable through the egg shell.

The egg takes about 5.5 days to mature. The young caterpillar nibbles away a portion of the egg shell to exit and proceeds to devour the rest of the egg shell. It has a pale yellowish body bearing reddish patches. The body has an initial length of about 2-2.2mm, and is covered with dorso-lateral and lateral rows of long setae. At the posterior end, there is a pair of short backward-pointing processes. Its yellowish brown head features a number of setae and has a pair of short and rounded horns and a few lateral protuberances which are smaller.

Two views of a newly hatched caterpillar, length: 2.2mm.

As a result of its leaf diet, the 1st instar caterpillar soon takes on a strong greenish undertone, and reddish patches on its body fade away in a day or two. Narrow, whitish bands appear dorsally, dorso-laterally and laterally. The first instar lasts about 6.5-7 days with the body length increases to about 5mm.

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

Two views of a 1st instar caterpillar, late in this instar, length: 4.6mm.

Two views of a late 1st instar caterpillar, dormant prior to its moult, length: 5mm.

In the 2nd instar, the head turns pale greenish in colour. The body color is pale yellowish green. There are numerous, tightly spaced, tiny, whitish protuberances on the body and the head, each with a setae emanating from it. The two anal protuberances are now proportionately longer and more pointed. The 2nd instar lasts about 7-8 days with the body length reaches about 7.5mm.

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

Two views of a 2nd instar caterpillar, length: 7.5mm.

Two views of a late 2nd instar caterpillar, dormant prior to its moult, length: 7.2mm.

The 3rd instar caterpillar mostly resembles the previous instar. This stage also takes 7-8 days to complete with body length reaching about 12mm.

Two views of a newly moulted 3nd instar caterpillar, length: 7mm.

Two views of a 3nd instar caterpillar, late in this stage, length: 12mm.

Two views of a late 3nd instar caterpillar, dormant prior to its moult, length: 10mm.

The 4th instar caterpillar bears a strong resemblance to the 3rd instar caterpillar with no obvious change of any features or markings. The 4th instar lasts about 8 days with body length reaching about 15mm.

Two views of a newly moulted 4th instar caterpillar.

Two views of a 4th instar caterpillar, length: 13mm.

Two views of a late 4th instar caterpillar, dormant prior to its moult, length: 14mm.

The next moult brings the caterpillar to its 5th and final instar. There is still no prominent shift in appearance. The two anal processes are now much shorter and less prominent than in the previous instars while the blanket of setae-bearing tubercles appear to be denser in this instar. In a period of about 12 days, the body grows to a maximum length of about 21-23mm.

Two views of a newly moulted 5th instar caterpillar.

Two views of a 5th instar caterpillar, length: 21mm.

Toward the end of the 5th instar, the body gradually shrinks in length. Finally the caterpillar finds a spot on the underside of a leaf blade to spin a silk pad. It then secures itself there via its anal end, and assumes its upside-down pre-pupatory pose.

A sequence showing the development of a prep-pupa of the Common Four Ring.

After about 1 day in the pre-pupal stage, pupation takes place. The green pupa is somewhat angular and longish, with a dorsal protrusion on the thorax and ridges defining the dorsal wing margins (which are colored dark-red). Length of pupae: 8.5-9mm.

Two views of a pupa of the Common Four Ring.

After 7 days of development, the pupa becomes darkened in color, and the subapical ringed-spot on the forewings can now be seen through the pupal skin in the wing pads. The next day the eclosion event takes place with the adult butterfly emerges to start the next phase of its life cycle.

Two views of a mature pupa of the Common Four Ring.

A newly eclosed Common Four Ring clinging on to its pupal case.

References:
  • [C&P4] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society, 1992.
  • 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 Bobby Mun, Nelson Ong, Frederick Ho and Horace Tan

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