Nokona regalis (Butler) and Toleria romanovi (Leech) (Lepidoptera: Sesiidae) are economically important pests of grape in northeast Asia. We compared the overwintering, damage and seasonal flight activities of these two species in Korean vineyards. Mature larvae of N. regalis overwintered in the infested shoots of grape, while T. romanovi overwintered as mature larvae enclosed within a cocoon in the soil. Larvae of the former species fed primarily in grape shoots (97.2%), whereas larvae of the latter species burrowed into main trunks (57.4%) and branches (40.4%), causing significant damage and frequent mortality. The seasonal fluctuation of male catches was monitored with pheromone traps in 2010. Male moths of N. regalis were present from late May until middle June, and peak abundance occurred in early June. T. romanovi males were trapped from early June to early August with peak catch in middle July in Suwon.