Clouds of Mayflies are moving up the Susquehanna River, and leaving behind them the bodies of thousands of mayflies. It marks the beginning of the annual “whitefly storm”… the world-famous whitefly hatch in which millions of the insects emerge for mating. They are attracted to light sources, and in the past have even caused problems for drivers due to masses of dead insects on lighted bridges and roads. The whole thing should be over by mid August.