Butterfly of the Month - October 2024

Butterfly of the Month - October 2024

The Orange Tailed Awl (Bibasis sena uniformis)

A pristine Orange Tailed Awl puddling on a damp log

We move past the final quarter of the year, and the month of October 2024 is almost over. The bird migratory season is in full swing, and the birder community in Singapore is having a busy time out in the field looking out for rarities that may have made their way over Singapore skies at this time of the year. The annual migration usually lasts over six months, ending some time in March or April the year after.

Over the years, Singapore's green cover has, surprisingly, increased, making the island a relatively conducive place for biodiversity to thrive.  Despite its highly developed built environment, the city's urban planning has taken into consideration the flora and fauna that co-exist with us. Whilst some activists continue to lament the removal of mature trees and the sacrifice of wild green areas for development, our city-state has to a large extent, been able to manage land use to allow nature and the built environment to co-exist in harmony.

Whilst it is always a compromise to accept our wild free-ranging fauna to share human habitats, Singapore has, in recent years has attracted a myriad of biodiversity that was not as prevalent in the previous decades. Today, residents accept (or tolerate?) hornbills, otters, jungle fowls, wild boars, civet cats and many other animals to share our urban spaces with us. No one bats an eyelid at the family of jungle fowls with their chicks in tow, foraging in the grasslands of our HDB gardens - a scene that was very rare in the 80's and 90's.

An Orange Tailed Awl puddling at a sandy streambank

With a tagline of a "City In Nature", was this by design or by coincidence? Can an urbanised city such as Singapore learn how to design its urban development around nature, instead of excluding it? We see more butterflies in our urban parks and gardens that have been curated to attract these flying jewels and their caterpillars. The landscape plantings in our urban greenery are no longer designed with pristine, regimented and aesthetic priorities in mind - they have been curated with more native planting and flora that attract and enhances the survival of our biodiversity in the city.

And over to our Butterfly of the Month for October 2024 - a relatively rare butterfly that has been classified as "Near Threatened" in the Singapore Red Data Book 3rd Edition. This Hesperiidae, the Orange Tailed Awl (Bibasis sena uniformis) was recorded as a newly discovered species for Singapore some time in the early 2000's when an individual was spotted in the Central Catchment Nature Reserves. A rarity back in those days, its caterpillars were subsequently found breeding in numbers at the Singapore Botanic Gardens!

Orange Tailed Awls feeding at flowering Leea bushes - Top : Red Tree Shrub (Leea rubra) and Bottom : Bandicoot Berry (Leea indica)

The species has been observed across the island, at Dairy Farm Nature Park, Upper Seletar Reservoir Park, Upper Peirce Reservoir Park and at some urban parks and gardens. Its caterpillar host plant, Hiptage benghalensis (Malpighiaceae), is not rare, but can be found in cultivated areas around the island. Adult individuals have been spotted feeding at flowering plants in the early morning hours and closer to dusk.

The Orange Tailed Awl is dark brown above and unmarked. The wings are long and sharp with hindwing tornal cilia a deep orange-yellow that is very obvious in pristine individuals. Males and females are almost indistinguishable. The underside has a broad shining white discal band on both wings and the wings have a slight purple-blue sheen.

The hairy legs of the butterfly take on the orange-yellow colouration of the hindwing cilia and the robust thorax and abdomen of the butterfly is covered with greenish-grey hue hairs. The large eyes of the butterfly are typical of the family Hesperiidae. whilst the antennae are dark brown and unmarked.

An Orange Tailed Awl perched upside down on a leaf in the warmer hours of the day

The Orange Tailed Awl has a habit of hiding under a leaf with its wings folded upright during the warmer hours of the day. It has a darting skittish flight and is hard to photograph except when feeding at flowering plants. Males are often encountered puddling at sandy streambanks and muddy footpaths in the nature reserves.

Text by Khew SK : Photos by Alan Ang, David Chan, David Ho, Khew SK, Loke PF, Bobby Mun, Nelson Ong and Horace Tan