[Hot Tabasco]

I trapped a feral cat once, and blasted it with the hose for a good ten minutes. Let it go and never saw it again.

I have done that in the past and it is very effective.......I just might try it again......

[TigersEye]

I trapped a feral cat once, and blasted it with the hose for a good ten minutes. Let it go and never saw it again.

That is probably the least expensive and most effective solution. However, if the temps are close to or below freezing it will kill the cat or at least make it very sick. If you catch it you could wait until morning for the hose-and-release treatment so it would survive to learn the lesson.