Adult female Tabanus nigrovittatus Macquart (Diptera: Tabanidae) were field collected from a salt marsh in Essex County, Massachusetts. The horse flies were transported back to and tested in the laboratory to determine the effects of octenol (1-octen-3-ol) on engorgement. Flies exposed to octenol strips had a significantly higher engorgement response compared with control flies. To our knowledge, this is the first study to demonstrate an important link between an odor stimulus and the feeding response in Tabanidae. Research examining the link between odor attractants and repellents on the engorgement response is lacking or limited in most hematophagous Diptera. Understanding the role odors have on ingestion is essential to knowing how to interrupt feeding behavior of blood-feeding arthropods, especially for important vectors.