Management of host-seeking canyon flies using a barrier trapping system

Barrier traps placed around an area to be protected were used to reduce the human attack rate of host-seeking canyon flies (Fannia benjamini complex) within the protective barrier. Canyon flies are a significant nuisance pest of humans and animals. These flies feed on tears, mucus, sweat, blood or other human and animal secretions and are attracted by host-associated odors, mainly carbon dioxide. The study was conducted in La Habra Heights, California, during June and July 2011, during the peak canyon fly activity season at this location. Barrier traps were CDC-type suction traps (without light) with CO₂ as an attractant. The minimum distance needed between a host and the barrier traps, to capture canyon flies before they detect and orient toward the host, was determined by fly capture by a human collector paired with a CO₂-baited trap which was alternately on and off, over varying distances from the collector. The least distance tested between the trap and a human collector at which the presence of a trap did not interfere with the catch of the collector, was determined the ‘minimum effective barrier distance’ and was used as the radius of the perimeter in the barrier trapping system, where eight CO₂-baited traps were placed in a circular perimeter around a human collector. Capture of canyon flies by the human collector was analyzed for a significant difference when the barrier traps were present or absent. The effectiveness of a barrier trapping system to protect against host-seeking canyon flies will be discussed.