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Official Magazine of the Nature Society (Singapore)
Mangrove Butterflies
of Pasir Ris

Enthusiast Simon Chan goes on the butterfly trail as he takes us on a guided walk through the mangroves of Pasir Ris

Many butterfly species may easily be observed
on the boardwalk through the mangroves
The saying "One man's meat is another man's poison" rings so true for mangroves. Many people abhor the smell emanating from them. Others are of the perception that these watery places are breeding grounds for mosquitoes. A minority depend on them to make a living while nature-lovers the world over cannot get enough of them.

Ecologically, mangroves provide areas where many fish and invertebrate species come to lay their eggs. The

Plain Tiger
Danaus chrysippus chrysippus
Photo by Steven Neo
hatchlings grow until they are old enough to return to the open sea. It is a sort of nursery for the young. Additionally, mangrove forests not only halt the erosion of the land by sea but actually increase land mass by trapping sand and mud that is carried in by the waves. In short, it is land reclamation.

It is an important habitat where a variety of unique plants and animals live, some of which can only be found here and nowhere else. An excellent example of this is a species of brackish water snail that is preyed upon by the larvae of a certain species of firefly.

Pasir Ris has a mangrove patch which is hidden in a secluded corner of this seaside haunt of joggers, picnickers and cyclists. On the way in, cutting across a grassy patch from the MRT train station, many tiny bluish grey butterflies can be seen fluttering close to the ground. Aptly named the Lesser Grass Blue, this species has a wingspan of about one centimetre that is grey on the underside with numerous tiny black spots and a luminous light blue on the upperside. Although very common in urban areas, they are easily missed because of their small size.

Approaching the outer extremities of the park, a few of us spotted a small dark brown shape disappearing into an area of long grasses. Closer inspection revealed a specimen of a subspecies of Mycalesis. Commonly known as Bush Browns, they are distinguished from other similar drab-looking butterflies by their numerous ocelli or ring patterns on the underside.

Passing by one of the many Pong Pong trees in the vicinity, a mangrove species once popular as a roadside tree, I could not help but hopefully cheek its leaves for caterpillars of the King Crow (Euploea phaenareta castelnaui). Exactly three months ago, I managed to find two of its black-and-white striped caterpillars on the same tree and have succeeded in seeing them to maturity. But alas, this time around they weren't any.

Following the boardwalk trail that led us into the mangrove forest, we came upon a fast-flying butterfly circling an Ixora bush overgrown with Mile-A-Minute creepers. Settling on the small whitish flowers, it displayed its striated dark grey underside and the distinctive black tornal lobe on its tailed hind wings. Rapala varuna orseis, as it is scientifically known, is a forest denizen but is an occasional visitor to the urban areas.

A short distance away, the boardwalk forks into two, forming a circle with clumps of mangrove vegetation in the middle. Perched high up among this lush greenery was a Chocolate Pansy, happily sun-tanning on a leaf. To hasten the drying of its wings, it flapped continuously, revealing its rich brown upperside contrasting with the matte black of its underside.

Our presence disturbed a Common Grass Yellow from its slumber. Totally yellow, except for thin black borders on its upperside, it was last seen flying in a wriggling fashion towards the shade of the forest. Further down the trail, a stone's throw from the second circle, we chanced upon an area infested with small red bugs. A knowledgeable member of our group remarked that they were Cotton Stainers, a pretty bug found mainly in the mangroves.

By now we were well on the path that cuts across the healthy-looking mangrove forest but it was a sad sight that greeted us. What we saw upset us. Plastic bottles of every kind littered the swampy forest floor.

Blue Glassy Tiger
Ideopsis vulgaris macrina
Photo by Phang Tuck Pew
Entering the domain of the third circle, we hit the jackpot for sure. It came in the form of a Blue Glassy Tiger feeding on tiny yellow flowers. We had a really good look at the specimen as it was just a metre away. This pretty species is usually found in mangroves as its caterpillar foodplant, a milkweed vine, prefers to grow in these swampy areas.
Turning right led us to hard ground and a viewing tower that offers a spectacular view of the canopy. Near the base was a flowering and fruiting Indian Cherry bush. Attracted by its white flowers was a Parantica algeoides algeoides, another mangrove species very similar to the Blue Glassy Tiger. This butterfly can be differentiated from the other species by its overall darker appearance. It also has an 'unbroken' cell at the top of its forewing, unlike the Blue Glassy Tiger which sports an additional marking there.

Parantica algeoides algeoides
with its scent brush extruded
Photo by Phang Tuck Pew

Another mangrove-dependent species, the Mangrove Tree Nymph (Idea leuconoe chersonesia), was still commonly found in our mangroves at the turn of the 20th century. Singapore's rapid development has all but reduced mangrove habitats to what it is today. Having lost vast tracts of mangroves that it depended on for survival, this graceful species finally succumbed to local extinction.

'Samurai-face' stink bug
Photo by Ong Kiem Sian
Leaving the tower behind us, we passed by a row of Ixora bushes on our left. Suddenly, something white and yellow shot out from the bushes. It buzzed around and then landed on a leaf. We realised then that there were more of these creatures. A colony of this Man Face or Samurai Face stink bug was later discovered breeding on these bushes.
Out in the open area of the park, we had left far behind the sights and smells of the mangrove. Bordering the forest fringe, a multitude of plant species was identified, mainly, Singapore Rhododendron, cassia and many more. Circling a cassia bush was a lone male Lemon Emigrant, obviously looking for a mate.

Deciding against backtracking, we continued our walk on the footpath back to the entrance of the park. Flashing colours of black and white, a Common Mormon was seen swinging in and out of the fringe.

On our way back to the MRT station, a Plain Tiger appeared out of nowhere and flew across the side road before disappearing in a haze long grass. Once fairly common, this local species is threatened with extinction. Unless the host plants, the Crown Flower and Blood Flower are grown extensively, this beautiful insect will go the way of the Dodo.

Fighting over territorial rights, two male Blue Pansy butterflies were spotted chasing each other all over the grassy land. In the midst on this unfolding drama, a lone and fresh specimen of the Peacock Pansy could he seen enjoying the show.

At the end, we managed only to see two of a number of the known mangrove species recorded in the park. Our remaining mangrove forests must be conserved, not just for these butterflies, but for many other mangrove-dependant plants and animal species. At the same time, all of us can do our part for the environment and not pollute by littering.

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