The Yellow Streak Darter (Salanoemia tavoyana)
A Yellow Streak Darter resting on a frond of a fern
We have passed the first quarter of the year and the world has become a lot more volatile and chaotic as we move into the 2nd quarter. Over in the USA and the rest of the world, 'tariff' has become the most searched-for word on the internet. After the US President rolled out his Liberation Day measures, the economic world suffered a nasty shock as billions were wiped off the stock markets around the world. And as if riding a roller coaster, the markets reacted violently to policy reversals - up and down, in just a matter of days.
And it's not something that is going to be over quickly as a new normal will begin to change how the world moves on from this. The trade war's victims will probably be the average man-in-the-street who will have to struggle with an even higher cost of living to cover daily essentials and necessities. It is amazing how global equilibrium can be disrupted so easily by one man and in so short a time without resorting to any violence or hostilities... yet.
Over in Singapore, election fever has gripped the population, as Nomination Day and Polling Day have been confirmed for 23 April and 3 May respectively. In an already chaotic world, how will the incumbent political party fare with the citizenry? Will the ruling party wrest back constituencies that it lost in the previous election? Or will it lose even more ground to an already strengthening opposition presence? The electorate will decide in a couple of weeks' time.
April 2025 is an unusually wet month for the region, with storm surges causing flash floods in Malaysia and Singapore. Commensurately, butterfly activity has also been lacklustre and low. The wet and cooler weather seems to have put a dampener on the numbers of butterflies out and about in our favourite butterfly hunting locations all around the island.
A Yellow Streak Darter perched on a leaf of its caterpillar host plant, the Mangrove Fan Palm
This month, we feature yet another "exotic" or non-native species that was a new discovery for Singapore when it was first observed and recorded in Feb 2011 on the offshore island of Pulau Ubin - the Yellow Streak Darter (Salanoemia tavoyana). First observed at a heavily shaded area near the Sensory Trail on Pulau Ubin, it has since been spotted elsewhere on Ubin at other locations where the caterpillar host plant, Licuala spinosa (Mangrove Fan Palm) grows. The host plant is not rare and is found on Singapore island where it is often used as a landscaping plant in many parks, gardens and roadside greenery.
The species was described as "known only from South Burma, Kedah and Langkawi", so it's a mystery as to how it appeared in Singapore! After its discovery, it has continued to be regularly seen on Pulau Ubin, although observations of its caterpillars far outnumber observations of the adult butterflies. The unique eating pattern of the caterpillars and the construction of leaf shelters make them easy to spot on the Mangrove Fan Palm that grows all around the island.
The upperside of the Yellow Streak Darter is brown with a series of hyaline yellow spots and streaks. There is a prominent yellow streak on the basal half of the forewing. There are two yellow cell spots which are the diagnostic feature of this species. The antennae are yellow just below the apiculus with the shaft banded with yellow and brown. The eyes are a solid dark brown and large.
The underside is a rich yellow with dark spots and a characteristically obviously yellow-centred cell spot. The marginal areas of both wings are a deeper orange-yellow. The abdomen is chequered with yellow and brown with the legs a solid orange-yellow and unmarked. The wingspan of the adult ranges from 29-32mm.
Yellow Palm Dart adults are usually observed perched on the uppersides of foliage in heavily shaded forested areas where they frequent. When disturbed, they fly off rapidly in the usual Skipper-like fashion. This species' field behaviour is reminiscent of related species like the Yellow Chequered Lancer and Chequered Lancer. The complete life history has been recorded on this blog here.
Text by Khew SK : Photos by Khew SK, Koh CH, Richard Ong, Michael Soh, Simon Sng, Horace Tan and Zick Soh.
Further Reading :