21 September 2013

Butterfly of the Month - September 2013

Butterfly of the Month - September 2013
The King Crow (Euploea phaenareta castelnaui)

The first week of September saw another unprecedented flood in Singapore - this time on the western side of the island near the National University of Singapore. For the first time, an entire major expressway was completely shut down to all classes of vehicles for about 40 minutes. The Ayer Rajah Expressway, or the AYE was inundated by the sudden downpour in the early morning hours, and coupled with the high tide, caused the flooding of all four lanes.

This 'rainy season' that is known as the South-West monsoon has seen several wet days in September, including weekends, that caused ButterflyCircle members to be cooped indoors (rather unhappily) instead of going out on their regular outings. The 'Sumatras' as these seasonal monsoon winds are called, are forecasted to taper off in October as the inter-monsoon lull will hopefully bring better weather.

For the nature groups, the concerns over the 50km Cross Island MRT line that will start in Changi and end in Jurong will be given a short reprieve as the Land Transport Authority announced that a two-year Environmental Impact Assessment will be conducted to ascertain the impact on biodiversity and the habitats where the line cuts through MacRitchie Nature Reserve. Some initial thought-provoking questions can be found on this site. The NSS also published a position paper on the concerns regarding the initial soil investigation works, as well as the potential ecological damage that the underground tunnelling work may cause during the construction stage.

Dr Wee YC, the author behind the Bird Ecology Study Group, has also penned a series of articles showcasing the biodiversity that may be lost with the Cross Island Line, if it goes ahead as planned. His latest article is posted here. A site to showcase the biodiversity of MacRitchie forest, and to lobby concerned nature enthusiasts and anyone who shares the common cause has been set up. It's called the Love Our MacRitchie Forest site.

Our feature butterfly for the month is the largest species in the genus Euploea often referred to as the 'Crows'. The genus features large distasteful butterflies, usually black or blue, with white spots or stripes on their wings. The King Crow (Euploea phaenareta castelnaui) is the largest member of the genus, with a wingspan between 90-105mm.

The King Crow is a moderately rare species, although it can be regularly observed in local areas, particularly where its caterpillar host plant grows. It is often spotted in the back-mangrove areas of Pasir Ris Park, Pulau Ubin and even in urban areas in the vicinity of its host plant, the Pong Pong Tree (Cerbera odollam).

On the upperside the predominantly dark brownish-black butterfly features a series of violet-tinged apical spots on the forewings. There is a series of white marginal and submarginal spots on both wings. The spots on the underside are smaller although there are some individuals where some of these spots appear violet in colour.

On the upperside of the hindwings, male King Crows feature a raised scent patch in the cell, and there is a certain obvious discolouration at the tornal area of the hindwing. The forewing dorsum of the female is straight, whilst in the males, the forewing dorsum is strongly bowed. Females are typically larger, with a wider wingspan.

The King Crow flies slowly but can be alert and skittish. It tends to fly at higher levels amongst the treetops, stopping occasionally to rest with its wings folded shut. At times, the butterfly is observed to rest with its wings opened flat, as if to sunbathe. It can also be observed feeding on a variety of nectaring plants, and is particularly attracted to the flowers of the Syzygium trees.

The caterpillar host plants were previously planted as a roadside tree and in some housing estates. But in recent years, the tree has fallen out of favour, as the large apple-like fruits have been known to drop and damage parked cars, prompting the authorities to remove the Pong Pong as a roadside tree. It is now more often seen in backmangrove areas and parks, away from carparks.

The complete life history of the King Crow has been recorded in this blog here.  The photo below shows the eclosion sequence of the King Crow.

Text by Khew SK : Photos by Sunny Chir, Khew SK, Loke PF, Bobby Mun, Horace Tan, Tan Ben Jin & Benedict Tay