Mating behavior of Euproctis similis (FUESSLY) was observed under both laboratory and field conditions. Mating started 2 to 5hr after the lights were off and continued for 156min in the laboratory (23°C, 16L-8D), whereas it began 0.5 to 3hr after sunset and continued for 162min in the field. The maximum mating rates were recorded with 3 to 4 day-old moths.