A giant silk moth fresh from the monsoon dark
Late one August night in Medog, this moth came to the light and instantly silenced the room. It was huge, its wings patterned in rich browns and tan, with clear eyespots and softly scalloped edges. Like most giant silk moths, it sat calmly, as if it had all the time in the world, which it almost does not.
This is Antheraea formosana, a giant silk moth in the family Saturniidae of the order Lepidoptera. The genus Antheraea includes the famous wild silk moths, whose cocoons have been spun into tasar silk in Asia for centuries. The species name formosana refers to Formosa, the old name for Taiwan.
Giant silk moths live on a clock. The adults have no functional mouthparts and never eat; they emerge from the cocoon, find a mate within days, lay eggs, and die. All the feeding happens in the caterpillar stage, which chews through tree leaves for weeks to store the energy for that brief adult flight. The feathery antennae of the males are built like chemical sensors, tuned to find a female across a dark forest. The big eyespots on the wings are thought to startle birds into hesitating, just long enough for the moth to slip away.
Its name points to Formosa, the old name for Taiwan, and meeting it in the wet forests of Medog felt like a glimpse of something ancient and fragile. It would be gone by morning, but for one night it was the biggest, strangest thing at the light.
