The wingspan is 45–65 mm. The moth flies from June to August depending on the location.
The larvae feed on various grasses and reeds. The species' common and scientific names derive from the larva's supposed drinking of drops of dew Description Wingspan 45–65 mm. The yellowish females are slightly larger than the orange-brown male but both sexes usually show the two distinctive white spots on the forewing. Habitat Most frequent in marshy places and riversides but also in drier grassy terrain. When to see it Flying at night, in July and August, the males especially are attracted to light. Life History This species gets its English (and Latin) name from the habits of the caterpillar which is supposed to have a liking for drops of dew. Grasses and reeds form the bulk of the foodplants. UK Status The species is fairly common in the southern half of Britain. In a recent survey to determine the status of all macro moths in Britain this species was classified as common. VC55 Status Fairly common in Leicestershire and Rutland, but possibly declining. L&R Moth Group status = A (common and resident).