Australia has just under 11,000 species described, contained within 91 families. Of these around 400 species belong to the butterflies, the remainder to the moths, but there could possibly be a further 20,000 species of moths yet to be described. Both groups are superficially similar in appearance, but the butterflies differ from the moths basically by being diurnal (although some moths are also diurnal), having clubbed antennae (often hairy or feathery in moths, but can be clubbed in some species, such as Synemon sp.) and by generally holding their wings upright when perched (often outspread or domed over the back in moths). Both groups have compound eyes and coiled proboscis. Larval caterpillars have three pairs of legs on thorax and hook-tipped prolegs on most other body segments.