Genus: Udaspes Moore, 1881
Species: folus Cramer, 1775
Wingspan of Adult Butterfly: 37-45mm
Caterpillar Local Host Plants: Cheilocostus speciosus (Costaceae, common name: Cane Reed, Spiral Flag, White Costus), Costus lucanusianus (Costaceae, common name: African Spiral Flag), Hedychium coronarium (Zingiberaceae, common name: White Ginger Lily, Butterfly Ginger), Zingiber officinale (Zingiberaceae, common name: Ginger), Curcuma longa (Zingiberaceae, common name: Tumeric).
Physical Description of Adult Butterfly:
Above, the wings are dark brown. The forewing has large white hyaline spots in spaces 1b, 2 and the distal end of the cell. Smaller white spots are found conjoined in spaces 3 and 4, singly in space 5, and conjoined in spaces 6 to 9. The hindwing has a large white discal patch with irregular outline. Underneath, the wings are reddish brown. In the hindwing, the tornal area is paler brown with the large white discal patch extended to wing base. A large irregularly shaped dark brown spot occurs in spaces 1b and 2. The antenna has a whitish band just below the club.
Field Observations of Butterfly Behaviour:
Grass Demon is moderately common in Singapore. The adults are typically found in parks, park connectors and gardens where one of its many host plants in the Zingiberaceae and Costaceae families are cultivated. The adults are fast fliers among the ground cover and shrubbery. They have been observed to visit flowers for nectar, and perch on sun-bathing spots with open wings.