What Bug Is That? The guide to Australian insect families.

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The adults are relatively stout-bodied and nocturnal. Imma acosma is the best known Australian species (Common 1979); it occurs in eastern Qld and N.S.W.; the green larva feeds fully exposed on the foliage of Hymenanthera dentata and pupates in a white, silk cocoon beneath a network of silk stretched across a slight hollow. I . lyrifera from North Qld has partly transparent hind wings and I . stilbiota is a large, noctuid-like species from Qld and the Torres Strait islands. At least one unnamed species is known from north-westerm W.A. The black and orange Birthana cleis , the most conspicuous Australian species, occurs in N.T. and North Qld.


Small; head smooth, with lamellar scales; ocelli usually absent, chaetosemata usually present; antennae filiform; proboscis well developed, unscaled; maxillary palps minute, 1- or 2-segmented; labial palps curved upwards; 2nd segment with dense scales, apical segment slender and pointed; epiphysis present; spurs 0-2-4; hind tibiae smooth-scaled; fore wing with male retinaculum on Sc, chorda and stem of M absent in cell, R 4 and R 5 sometimes stalked, R 5 and sometimes R 4 to termen, CuP present near margin, 1A + 2A fork prominent; hind wing sometimes partly transparent, female frenulum of 3 bristles, vestigial M-stem present in cell, Rs and M 1 usually stalked, CuP present near margin, 3A present; abdomen sometimes with coremata. Larva slender, without secondary setae, more dorsal setae barbed, prothorax with 3 L setae on one pinaculum; ventral prolegs slender with crochets in uniordinal mesoseries; feeding exposed. Pupa slightly compressed, lightly sclerotised, abdominal terga without spines, segments 5 and 6 movable; without cremaster but with about 16 hooked setae; cocoon of white silk, pupa not protruded at ecdysis.