A derlac whistle was a device that ranchers used to call derlac cattle. Before inheriting a position as a Vigo in Black Sun from his mother, Shal'mak, the Kian'thar Kreet'ah spent time on his father's derlac farm on his homeworld of Shaum Hil, corralling the cattle with a whistle as well as selling them for export.
- Shadows of the Empire Sourcebook