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Milionia Walker

Type species: glaucans Stoll, Moluccas.

Synonyms: Bizarda Walker (type species optima Walker = rawakensis Quoy & Gaimar, New Guinea); Cnissocnema Bryk (type species neuhaussi Bryk - callima Rothschild & Jordan, New Guinea).

This genus contains a diversity of species, most of which are characterised by iridescent blue black facies, highlighted with bands of red, orange, yellow or iridescent greenish blue. Most are found in the New Guinea area and hence may be mimetic, so a generic definition is most reliably based on structural characters, particularly of the male genitalia. (Holloway, 1984b)

The male antennae are ciliate; the eye is hairy in some species; the forewing fovea is not present. The abdomen has a comb of setae on the third sternite. In the genitalia the uncus is apically bifid. The tympanic cavi are large. The gnathus is narrow, particularly over the apical fused part. The dorsal surface of the tegumen has a mass of fine, deciduous setae that is most dense towards the junction with the uncus. In some species, e.g. M. callima and M. philippinensis Rothschild, the setae and their basal scars are more robust. There is also usually a dense mass of setal hairs with a distinct flexure on the interior of the valve towards the base (peniculus?), but this feature is also seen in some Bracca taxa. The valve ornamentation probably provides the best diagnosis. The group of more or less basally directed setae marking the distal part of the cucullus is subapical and set in from the margin of the valve; the sclerotised band from the cucullus to the sacculus extends basad before looping back to meet the interior of the sacculus sclerotisation at a row or group of robust setae. M.fulgida Vollenhoven and a few other species have a digitate process with setae at the apex just interior to the centre of the valve costa, and more extensive groups of spines on the saccular sclerotisation which is expanded to subsume the central band. The aedeagus usually has a single, reversed, robust cornutus on its tubular vesica.

The female genitalia have a typical boarmiine bursa and signum but the ostium is set well anterior to the eighth segment and there tends to be more sclerotisation on the antevaginal lamella.

The life histories of a few species have been investigated, and some are regarded as forestry pests. The indications are that the genus is a conifer specialist, particularly on Podocarpaceae and Araucariaceae, southern hemisphere families that extend north to eastern Asia (Tho, 1978; Wylie, 1974).

Wylie recorded M. isodoxa Prout as a major pest of Araucaria in plantations in Papua New Guinea. He published details of the life history of this continuously brooded species. The larvae are brown with yellow dorsal stripes and oblique lateral bars on each segment. The biology of M. basalis Walker is described below.

Many species are day-flying but others come to light at night The genus is most diverse in the Australian tropics and attenuates westwards into the Oriental tropics, with only a few species occurring in mainland Asia.

The genera Callhistia Druce and Eumilionia Thierry-Mieg, associated with Milionia in the BMNH, are distinct. The male genitalia are significantly different from those of Milionia, and both genera have a pair of coremata between the 6th and 7th segments.

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