This diurnal Zygaenid moth, Pompelon marginata has electric blue wings covering red underpart that shows proudly only when it flies. This signals its toxicity - it is a cyanogenic moth - manufacturing and storing the respiratory toxin hydrogen cyanide. Caterpillars of Zygaenid moths feed on cyanide containing plants and then went on to manufacture more on their own, exuding them in form of a yellow brown liquid form along its body when disturbed. Many species carry this toxin to their adulthood.
G.M. Tarmann (A revision of Australian Zygaenidae) mentioned an interesting account in 1959 whereby a lady named Miriam Rothschild exposed 2 drops of such brown liquid on an open needle wound on her forearm. This liquid was obtained from a Burnet Moth, a relative from the temperate climate. This is what he said: "Almost immediately, sensations of breathlessness occured, associated with sweating and rapid pulse rate that increased to 120-130 beats per minute." The symptom persisted for several hours.
Well, she sure was lucky it was not from something more noxious.....like an American arrow poison frog.
This critter was found in fluttering at Bukit Panjang park.
Many thanks to Mr Gan from the Singapore Butterfly Interest Group for the ID.