The metal prongs you see on plane wings are static discharge wicks, providing protection against static electricity
If you travel on an airliner this summer, you may notice a series of metal prongs projecting from the trailing edge of the wings. These are often misidentified as lightning rods; in fact, they provide protection against static electricity.
Anyone who regularly walks on a nylon carpet knows that you can pick up static charge by a process of frictional charging. This can give you an unpleasant electric shock when you touch a metal door handle. Something similar happens to an aircraft flying through rain or dust particles, as it picks up a tiny amount of charge from contact with each one.