Mythimna (Acantholeucania) yu Guenée

Leucania yu Guenee, 1852, Hist. nat. Insectes, Spec. gen. Lepid ., 5: 78.

Leucania exempta Walker, 1857, List Specimens lepid. Insects Colln. Br. Mus., 11: 710.

Leucania costalis Moore, 1877, Proc. zool. Soc. Lond., 1877: 603.

Leucania yu Guenee; Calora, 1966: 657; Holloway, 1976: 9.

Diagnosis

The forewing is rather unusually patterned with a narrow, triangular, pale wedge over the cell, edged with dark brown distally and posteriorly that diffuses away towards the margin. The antemedial and postmedial fasciae are more entire, less regular in course, though crenulate, than in other Mythimna; the antemedial is associated with a strong brown spot, possibly the orbicular, in the cell.

Geographical range

Oriental tropics east to Fiji and Tonga; absent from New Caledonia.

Habitat preference

On G. Kinabalu the species was noted in small numbers in cultivated areas at 1050m and 1200m. In Brunei singletons have been taken in swamp forest at Daerah Belait and on the coast at Seria.

Biology

The larva of the Javan population was described by Piepers & Snellen (1906). It is smooth, green, or yellowish, ochreous or pale red when young, becoming brown marked with yellow or red when older. There are faint longitudinal bands and small white spots, whilst the venter is marked by a white or yellow band. Sevastopulo (1944, 1945) described similar larvae from India, giving the colour of the mature larva as olive-brown. He described the strong subspiracular white stripe and indicated that the dorsal and subdorsal stripes become fainter through the instars, almost disappearing in the fully grown final instar.

The larva feeds on grasses (e. g. Paspalum) and has also been recorded from Saccharum (Piepers & Snellen; Robinson, 1975).