Living in Florida, about half of our service calls involve ants in the switch. These little guys are so tough that when the pressure switch calls for water and there is an ant walking across the points that are going to close on him, his little body keeps the points from touching and the pump from starting. Sometimes after a while the potential current at the points will start burning the ant until the points again come together. Or you will have to manually flick the points to get them back together.
I tell my customers to spray all around the switch, the pipes they walk up as well as the conduit housing the wires. This won't stop them from coming through the conduit mind you. But spraying is the best answer I have.
I tried moth balls on someones advice. They ate it; I think. Andro just moves the hill over three feet or so. And the chemicals that would work good have all been banned.
So just call us when the water stops and we'll come out and flick your switch points, charge you $69.00 and go away till next time.
bob...