Thank you to Bill Avery for contributing this image. The Mediteranean Fruit Fly ("Med Fly") invasion, which could have wiped out Florida's citrus crop, required massive spraying from twin engine aircraft at very low altitudes over all of Hialeah, plus other areas of South Florida. In order to spray evenly these balloons were raised at each end of the next pass to be made by the spray aircraft. After the aircraft passed over the balloon, the handler would then pace off the required number of footsteps, stop and raise the balloon so the aircraft could line up with the two balloons to make the next pass. It was great fun feeling the mist hit your skin and inhaling the aroma of the pesticide or whatever it was.