Also, does fly spray expire? Years ago I had this fly spray that came concentrated and you put water in it to deconcentrate it to use and fill the bottle. The bottle is pure white with a blue spray nozzle. I bought it at a nearby tack place. It worked wonders! After I bought it, my trainer moved and I had to find a new barn. The place where I ended up I rode a horse that was very sensitive to fly spray and had to use a special kind, so mine has just been sitting. Do you think it would still be safe to use or should I just throw it out?