Baited for hundreds of fly species which are most common in agricultural areas -- including house flies, false stable flies, blow flies, bottle flies, flesh flies, face flies and many others. The trap contains a fast-acting fly attractant that starts working as soon as you add water. Food and feed additives are combined with other dried ingredients to make the Rescue!® attractant. Lured by the scent, flies enter through the yellow top cap and drown in the water. Designed for areas with heavy fly concentrations, the trap holds up to 40,000 flies. It will help control the fly population outside before it ever becomes a nuisance inside. For outdoor use only. Active Ingredients: Sucrose; Whole Egg Solids; Yeast; Trimethylamine; Indole; Other