08 September 2019

Butterfly of the Month - September 2019

Butterfly of the Month - September 2019
The Common Duffer (Discophora sondaica despoliata)

A portrait of a butterfly : A freshly eclosed Common Duffer perched on flowers of Lantana camara

We tread into the 9th month of 2019 as the summer heatwave begins to ease off slightly. Already, there have been reports of torrential rains and floods affecting certain countries around the world. As the monsoons bear upon countries like India and parts of Indo-China, the intensity of rainfall and volumes have changed over the decades, making predictions and flood-mitigating measures difficult.

Singapore prepares for climate change, as outlined in Prime Minister Lee's National Day Rally speech last month, by (1) understanding the issue (2) take measures to mitigate it and (3) adapt to it. As a low-lying city state near the equator, Singapore is more vulnerable to sea level rise than most countries.

As it is, various pilot projects have been tested to prevent local infrastructure from being affected by rising sea levels. Platform levels for new infrastructure is being raised, and new developments are required to be built at least 4m above mean sea level. Research on polders and dikes are being carried out on the offshore island of Pulau Tekong and these experiments are likely to be implemented in a large scale on the main island of Singapore in time to come.

A Common Duffer typically lurks in dark shady vegetation 

In the meantime, the Cross Island MRT Line is back in the news. The future Cross Island MRT Line that will stretch from Tuas to Changi can either run under the Central Catchment Nature Reserve or go around it. Generating controversy for the past few years, nature groups continue to be up in arms against the MRT line cutting across the nature reserve. The initial feasibility studies have shown that both options can be made to work. Furthermore, the MRT line that cuts across the CCNR will now be planned to be 70m deep under the nature reserve, instead of 40m as originally intended.

A Common Duffer feeding on some nutrients on a twig

The decision of the alignment of the MRT line will be made some time next year. Both nature groups and the public, particularly the homeowners whose properties may be affected by the option to skirt the MRT line around the nature reserve, say their piece for or against either option. The two options obviously have their respective pros and cons, and the government will make a final decision soon.

We come back to our feature butterfly for the month of September 2019, the elusive Common Duffer (Discophora sondaica despoliata). The species is anything but common, as what its English common name suggests. Adults are rarely seen in Singapore, although it is quite widely distributed across the island. It can be found in the vicinity of its host plant, bamboo (Bambusa spp.)

Two female Common Duffers

The butterfly has been observed, usually singly in heavily shaded forested areas. But it can also be found in areas around bamboo groves, like the Singapore Botanic Gardens and even on Pulau Ubin. The Common Duffer lurks amongst heavily vegetated areas, staying quite still unless disturbed. It is skittish and is hard to approach when disturbed from its hiding places.

The Common Duffer is dark brown with a series of obscure pale blue spots on the apical half of the forewing in the male. The female is also a similar shade of brown on the upperside, but with a series of mauve post-discal spots and sub-marginal spots on the forewing and orange post-discal and sub-marginal spots on the hindwing. The female has a more pronounced protrusion at vein 4 on the hindwing making the hindwing appear slightly more angular.

A female Common Duffer perches on palm leaves

The underside is ochreous brown and heavily striated with the distal half of the wings a lighter shade. There are a few post-discal eyespots on the hindwing. In a sidelight, there is a purplish wash on parts of both wings.

A Common Duffer from Hong Kong feeding on some organic matter

Two Common Duffers from North Thailand

Males of the species have regularly been observed to puddle on decomposing organic matter and along damp footpaths that have been tainted with animal excretion. Females are more often seen feeding on overripe fruits and in particular the fruits of the Singapore Rhododendron (Melastoma malabathricum)

The hairy caterpillars of the Common Duffer resemble moth caterpillars

Occasionally, its caterpillars can be found in small numbers on its caterpillar host plant, bamboo. The caterpillars are typical of the genus in the sub-family Satyrinae and are hairy and moth-like. Early instar caterpillars are gregarious and often feed in a group.

Text by Khew SK : Photos by May Chan, Antonio Giudici, Federick Ho, Khew SK, Loh MY, Jonathan Soong and Liyana Zolpakar

Special thanks to Foo Jit Leang for discovering several clutches of caterpillars on the bamboo plants near his home to allow us a chance to observe and photograph the Common Duffer more easily

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