A bright orange butterfly called Tawny Coster has now established itself across much of northern Australia.

Dr Michael Braby, who first identified them after reports from a local naturalist, said “When they fly they seem to reflect the sunlight quite vividly so they look almost like a hot flame”.

The Tawny Coster has spread east as far as Groote Eylandt, and has been spotted in Broome. As Dr Braby began his studies of the Tawny Coster, he found that it was a species originally from India and Sri Lanka, and “first detected in Thailand in 1984, and then in the last 30-odd years, it has been moving steadily through south-east Asia”.

According to Dr Braby’s research, unlike many other invasive species, the Tawny Coster is not having any negative environmental impact. New butterfly species are only known to have established in Australia twice before over the last 200 years. The Cabbage White Butterfly was introduced to the east coast of Australia in 1929 with vegetable imports from New Zealand, and the Wanderer, or Monarch Butterfly, managed to establish in Australia as early as 1871, after its milkweed host plant was introduced.

When Dr Braby identified the bright orange butterflies as Tawny Costers, he knew if they established themselves, he would be witnessing a rare event. While the idea of a delicate butterfly crossing 700-plus kilometres of the Timor Sea to northern Australia may seem unlikely, Dr Braby said it was well within their capabilities.

“Butterflies can look like weak fliers when you see them flying slowly around near the ground, but when they want to move they really can,” he said.

Story source: http://www.abc.net.au/news/2015-11-16/indian-butterfly-crosses-asia-and-invades-northern-australia/6916980