Responses of tabanids to Nzi traps baited with octenol, cow urine and phenols in Canada.

Cow urine and the two phenols responsible for the attraction of biting flies to cow urine (4-methylphenol, 3-n-propylphenol) were compared with octenol (1-octen-3-ol) as baits for Tabanidae. Relative to an unbaited Nzi trap, catches of the horseflies Hybomitra lasiophthalma (Macquart), Tabanus similis Macquart and Tabanus quinquevittatus Wiedemann (Diptera: Tabanidae) were increased by 1.5-2.6, 1.4-2.0 and 1.4-1.9 times, respectively, whenever a bait included octenol released at either 0.13 mg/h or 1.5 mg/h, regardless of the presence of phenols or urine. Catches were not affected when traps were baited with phenols alone at evaporation rates of 0.38 mg/h (4-methylphenol) and 0.022 mg/h (3-n-propylphenol). Catches of Hybomitra horseflies were increased by 1.5-1.9 times with cow urine and 2.6 times with cow urine + octenol. This bait combination could prove to be particularly useful for Hybomitra horseflies, the common tabanids of northern environments.