Fly traps are available in several different forms, which use pheromone attractants to trap the flies in a container containing water, in which the flies drown. Most of the ones made for domestic/garden use are opaque, and look like hanging decorations or lanterns. They are poison-free and quite effective, though they do require emptying and refilling regularly unless they are the disposable type, which are more expensive. This type of trap is also available for wasps. Other "sticky" traps are available which don't look as unsightly as fly papers. If you need any further info, feel free to PM me.
No man knows true happiness until he's married......but then it's too late!
Proud member of the Greater Manchester Bushcraft Group