12 October 2019

Butterfly of the Month - October 2019

Butterfly of the Month - October 2019
The Lance Sergeant (Athyma pravara helma)

A Lance Sergeant sunbathing on top of a fern

We are now into the 10th month of the year 2019, and climate change and environmental issues continue to dominate the news in the past few weeks. Besides the usual storms and typhoons making their usual rounds across the globe, the dreaded haze was back to choke several southeast asian countries again.

The last two significant haze years that were recorded were in 2013 and 2015 and a milder one in 2016. Memories of the 2013 haze, which was one of the worst in recent history, recorded a Pollutants Standards Index (PSI) of 401 in Singapore. Back then, schools were closed and the acrid odour of burning organic material hung in the air for days. Visibility was low, and the number of haze-related respiratory health cases spiked. The haze returned in 2015, albeit slightly less intense with a peak PSI of 317.

After 2015, the annual slash-and-burn farming plus the clearing of land for oil palm plantations, particularly in Indonesia, seemed to have been brought under control. In 2016, a minor haze with PSI readings in the low 100's affected Singapore again, but only for a short period before things went quickly back to normal. And as if to remind us of the spectre of choking air, the haze returned with a vengeance this year with the PSI crossing the 150 mark and the smell of burning in the air. Fortunately, the return of some wet weather helped and the air quality was back to normal after slightly more than a week.

One wonders how governments can be more effective in controlling open burning of forests in Malaysia, Thailand and Indonesia? The clearing of forests for the cultivation of commercially-beneficial crops appears to be the main cause of burning, as this is the cheapest and most expedient form of land clearance. However, the untold damage to the environment, and not to mention biodiversity, due to the fires is something that cannot be easily quantified. And so we wait with baited breath (and our N95 masks) for haze to hit us again in the coming years if things do not change.

On the global arena, teenager Greta Thunberg made the news with her impassioned plea to the governments of the world to do something about climate change, or face irreversible consequences that her generation will have to suffer in the decades ahead. Whether this will change anything, we will have to wait and see. However, planning ahead is something that Singapore is not waiting for any longer, and engineering and urban strategies are in progress to address the imminent rise in sea levels.

Our butterfly of the Month for October 2019 is the Lance Sergeant (Athyma pravara helma). This species is one of several black-and-white striped butterflies in the genus Athyma that can be found in Singapore. In an earlier article, we featured the Sergeants of Singapore, highlighting the five extant species of Sergeants that are found in Singapore.

Although recorded as a new discovery in the mid 1990's the Lance Sergeant, could have possibly been missed by the early researchers in their documentation of Singapore's butterfly fauna. It is moderately rare species, but the host plants that its caterpillars feed on are not uncommon in the forested nature reserves of Singapore. It is not rare in Malaysia - where it is widely distributed from lowland forests to sub-montane habitats like Fraser's Hill.

A Lance Sergeant feeding on the ripened fruit of the Singapore Rhododendron (Melastoma malabathricum)

The Lance Sergeant is a medium-sized butterfly with a forewing length of 24-28mm. It is black and white on the upperside, with the diagnostic unbroken cell streak that easily distinguishes it from the other lookalike species in the Athyma genus. This unbroken white streak stretches across the thorax, and ends on both sides of the forewing with a thickened club.

A Lance Sergeant puddling at a muddy footpath

The underside is a greyish-brown and similarly marked as in the upperside, with the basal area of both wings a dirty green. The compound eyes are transparent, whilst the underside of the antennae club is orange in colour, but black on the upperside. The Lance Sergeant is often encountered feeding on flowers of forest trees, fruits but is also as regularly observed puddling at damp muddy footpaths.

The life history of the Lance Sergeant has been successfully recorded in Singapore. The host plants documented are two species from the genus Uncaria. These plants have a characteristic pair of cat-like claws which are modified lateral branches at the base of the leaves. The pupa of the species has a golden metallic appearance that is reflective and at certain angles, makes the pupa appear to be empty.

Text by Khew SK : Photos by Khew SK, Nelson Ong, Horace Tan and Anthony Wong