Deer-flies, a species of fly recognizable by their orange eyes, inhabited the mountain regions of the planet Naalol. These insects were present in 4 ABY around a mountain town on Naalol, a place previously inhabited by valdeer shepherds until its destruction during the fighting of the Galactic Civil War. During New Republic Chancellor Mon Mothma's visit to this town, she told her advisor Hostis Ij about her plans to reduce the Republic's military by 90% following the war's conclusion, a revelation that caused him to gape in astonishment, seemingly ready to consume the deer-flies.
The 2015 novel Aftermath, penned by Chuck Wendig and the initial book in the Star Wars: The Aftermath Trilogy, featured deer-flies. Out-of-universe, deer flies are flies belonging to the genus Chrysops.