Most scatter or granular toxic fly baits are intended to be used against house flies, Musca domestica L. (Diptera: Muscidae). Attractants have been developed to make baits house fly-specific to avoid wasting bait on nontarget flies. Cyanarox Insecticidal Bait (IB) (formerly Zyrox Granular Fly Bait) appeared on the market recently and field reports suggested that stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae), were being attracted to the bait. There was little doubt that the toxicant, cyantraniliprole, which is formulated to kill house flies, should readily kill stable flies if enough is consumed, but it seemed highly unusual that blood-feeding stable flies would be attracted to the bait. Proof of concept tests were conducted to determine if stable flies would feed on Cyanarox IB. When confined in small cages, mortality exceeded 90% after a 3-d exposure. Stable flies (200) were released in each of two large windowless rooms and Cyanarox IB was placed in small containers at the label rate at floor level in four locations per room. Mortality reached 90% after a 5-d exposure, which indicated that stable flies were attracted to the bait, actively found it and fed on it. The Cyanarox IB Material Safety Data Sheet lists an undisclosed amount of sucrose as part of the bait composition. Stable flies are known to feed on many sugar sources in the environment and the sucrose associated with the Cyanarox IB may explain why stable flies find it attractive.