Drosophila tarphytrichia was described by Hardy (1965) from specimens collected from Manoa Falls on Oahu in 1949. This species is closely related to D. vesciseta based on the structure of the male genitalia (Kaneshiro et al.1995), but can be differentiated by distinct wing markings and the ornamentation of the front legs of the male. The thorax is almost entirely yellow to red with a tinge of brown on the top. The legs are yellow, with the tip of the front leg strongly flattened laterally and with a dense clump of black hairs. This species is 0.148 in (3.70 mm) long with wings 0.2 in (4.0 mm) long (Kaneshiro and Kaneshiro 1995). The larvae of Drosophila tarphytrichia feed only within the decomposing portions of the stems and branches of Charpentiera sp. trees (family Amaranthaceae) in mesic forest habitat (Montgomery 1975).