'Time' was the only thing that worked. They slowly went away. Everything we puny human's tried was useless and usually counter productive! A few thousand returned the next year but nothing like the 1st time! 1st year x-mission musta pegged their radar pretty good.
They would ball up so big across the lightning protectors that they would actually discharge 100,000 Watts to ground and we would have to scram around to get the transmitter back on line.
Coupla barrels of DDT might help.