Also Portland cement mixed with peanut butter. Make balls out of it. Put in a dish outside that is covered from rain. Maybe put some other birdseed etc in it to get the squirrels interested.
I cannot testify 100% on it but...... Just think of ways to lure them into eating the cement balls. Maybe peanuts in the shell?
At this point however, my efforts and results have become the stuff that dominates the block party conversations. The cayenne pepper was the final straw.