Noctuidae, the largest family in the order Lepidoptera with more than 35,000 named species, consists of moths of diverse size and shape but bearing the synapomorphies of 'noctuid ocelli' just above the compound eyes and a peculiar branching of the forewing's second median vein. The simple eyes are lost in some species and wild individuals are usually loath to permit close inspection of their finer traits, so other clues come into play when one is making a not ureasonable stab at identifying random moths in field and glade. A well-built abdomen covered with wooly setae; simple, rarely pectinate antenna; mottled forewings that hide pale, broad hindwings; and a kidney-shaped spot near the middle of the forewing – these are among the general features that define owlets in their traditional sense but offer no counsel for a clade that now includes well-known former families such as tiger moths, tussocks and nolids.
Larval noctuids, which may resemble the inching loopers of geometrids, often descend from their host plants to pupate in the soil, under leaf litter or in deadwood. This habit may shield the developing imagos from parasitoid flies and wasps, and has persisted in a genus with at least two species that thrive in tidal woods. Aucha velans, which has a yellow mark on the hindwing, and Aucha villiana, whose hindwings are uniformly brown, can usually be seen when clumsy bodies trudging through mud and mangrove flush dirty grey moths that dart off, fluttering close to the ground, to quickly land on a nearby trunk or pencil root, where they pretend to be one of many knobs or scars on a wall of mud-caked bark. Little is known about the adults' feeding habits, though they are said to be active in daytime. The caterpillars, according to D.H. Murphy, gnaw at the edges of Avicennia leaves until they tire of briny foliage and rappel unto the forest floor. There, on a landscape of growing mounds and perpetual waste, they crawl under rotting branches or algal mats, weaving in their beds a case of silk to cloak from wind and water their breakdown and transformation into creatures of powder that take no prisoners as they turn awry and watch the sea's slow, sure rise.