TRIBE ORGYIINI
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Orgyia osseata Walker comb. rev
   
Orgyia osseata
Walker, 1862, J. Linn. Soc. (Zool.), 6:125.
   
Orgyia dimidiata
Walker, 1862, J. Linn. Soc. (Zool.), 6:125, syn. n.
   
Rilia basivitta
Walker, 1865, List Specimens lepid. Insects Colln Br. Mus., 32: 436.


Orgyia osseata

Orgyia osseata

Orgyia osseata

Orgyia osseata


Orgyia osseata


Diagnosis.
This is a very variable species as illustrated. It has much narrower wings than postica, and the forms with grey or red zones along the costa, or with pale cream lineation are distinctive. The more typical brownish form can easily be confused with the next species. This can be distinguished primarily on male genitalia. The key feature is not so much, as suggested by Schintlmeister (1994) (who illustrated several specimens of osseata as araea: figs 26-29), presence or absence of a small angular process in the centre of the valve costa, just subbasally on the dorsal arm, but a short (osseata) versus long (araea) digitate process on the juxta. It is osseata, rather than araea, that has the angular process on the valve costa, though this is variable in development. The females of both species are winged, that of osseata (illustrated) having strong blackish marks costally and subdorsally, adjacent to the forewing postmedial.






Geographical range. Indian Subregion, S.E. Asia, Sundaland, Philippines.

Habitat preference. Most records are from lowland forest, disturbed and cultivated areas, where the species is frequent. It has been taken rarely up to 1618m.

Biology. Bell (MS) described the larva in S. India. It has the hair-pencils and dorsal brushes typical of the genus. The brushes are whitish, grading pale yellow towards the centre. The body is light green with pinkish dorsolateral bands, the verrucae within the latter being of the same colour. There is a dorsal black patch between A1 and A2, and a smaller one at the anterior of A3. The head is pale red, and the prothoracic collar is pink.

The larva has a wide host range, including Mangifera (Anacardiaceae), Averrhoa (Averrhoaceae); Durio (Bombacaceae); Dryobalanops, Shorea (Dipterocarpaceae); Acacia (Leguminosae), Eugenia (Myrtaceae); Ixora (Rubiaceae), Nephelium (Sapindaceae); Sonneratia (Sonneratiaceae) and Theobroma (Sterculiaceae) (Murphy, 1990; Kuroko & Lewvanich, 1993; unpublished IIE and FRIM records; S. J. Willott, pers. comm.).

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