The achaete-scute complex (AS-C) is a group of four genes (achaete, scute, lethal of scute, and asense) in the fruit fly Drosophila melanogaster.
In some groups of insects, the mesonotum is hypertrophied, such as in Diptera, Hymenoptera, and Lepidoptera), in which the anterior portion of the mesonotum (called the mesoscutum, or simply "scutum") forms most of the dorsal surface of the thorax.