mechanosensory chaeta microchaeta Note that entomologists working in other species may call such sensilla trichoid, but Drosophila biologists typically reserve this for only the very smallest hairs. The reference for the term microchaeta among Drosophilist dates back to at least Lees and Waddington (1942). hair VFB:FBbt_00005182 fly_anatomy.ontology setulae A sensillum of the adult whose external sensory structure is a hair or short thin bristle. FBbt:00005182 adult sensillum