Large Grass Yellow (Eurema hecabe)
Appearance: Upperside yellow with broad, black terminal band on the fore wing and narrow, black terminal band on the hind wing. Underside yellow with several dark patches. Two seasonal forms; the wet-season form has the dark patches on the underside very faint and indistinct compared to the dry-season form.
Wingspan: 3.7–4.0 cm
Season: Several generations all around the year.
Range: Tropical regions of northern WA, northern NT, and northern QLD. Migrants regularly reach the temperate regions of QLD and NSW in summer and autumn.
Habitat: Wide variety of habitats.
Photo: Underside, dry-season form. (Ingleburn, NSW, 13 / 03 / 2010)
The Large Grass Yellow is a very common and widespread species throughout the tropical regions of northern WA, northern NT, and northern QLD. During the summer and autumn, the butterflies often migrate southward and regularly appear in the temperate regions of QLD and NSW, sometimes as far south as Sydney. There are two seasonal forms, with the wet-season form having the dark patches on the underside very faint and indistinct compared to the dry-season form.
There are several similar species in the genus Eurema, in particular the Small Grass Yellow (Eurema smilax) and the Scalloped Grass Yellow (Eurema alitha). The Large Grass Yellow can be distinguished from the Small Grass Yellow through the presence of a black terminal band on the upperside of the hind wing and a large, sharp indent in the black terminal band on the upperside of the fore wing. The Scalloped Grass Yellow has the black terminal band on the upperside of the hind wing much broader compared to the Large Grass Yellow, but otherwise looks very similar.