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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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