WHEN I saw these butterflies (see photo, left) mating in my garden in Puchong, Selangor, something about them told me they were not from this part of the world.
 Their forewings were long and narrow, quite unlike those of the local species that I have seen and photographed in many, many years of butterfly-watching.
 Later, after transferring the digital files from my camera's memory card to a laptop, I pored over several books and found a photo match. It confirmed my suspicion that these were Heliconia butterflies (Family Heliconiidae).
 The name of the species is Dryas iulia, and it lives in Central and South America. This makes it an alien, or exotic, species in Malaysia, and the obvious question was: "How did these butterflies come to be in my neck of the woods, half-way around the planet from the Neotropical Region?"
 Some months later I found the answer

on the World Wide Web. Two articles in the Butterflies of Singapore blogsite deal head-on with the issue. You can read them here and here.
 Some scientists have conducted a study on the appearance of this exotic species in Thailand and Malaysia, and also examined pertinent issues related to it. You can see their findings here.
 Using DNA sequencing methods, they found that naturalised populations of this species in Thailand had originated from a butterfly farm, and the tested specimens had very similar DNA barcode sequences as Dryas iulia modesta, a subspecies native to Costa Rica.
 Sightings of this species breeding in the wild were first reported in 2007. Since then it has spread to Malaysia because of the availability of its larval food plants, species of Passifloraceae, including Passi- flora suberosa. ~ CFS, 27 Sept. 2018