Its hard to see exactly what's going on in the picture. Do you cut your Geranium back after flowering? I can't see much other than normal post-bloom scruffiness. Any chance of a close up of the problem you're talking about?

The leaves look like this then they turn brown. The plant itself is fine because you can see new green leaves coming on. I have had this flower for a long time and have never noticed this happening until last year. Should I cut it back and see what happens ?

I can't help you on a diagnosis, I'm afraid. We don't have cicadas here so I don't know what they do.

I would cut it hard back. Even completely healthy Geraniums need that periodically.

It looks like leaf spot to me. I'd cut it back and put the cuttings in the garbage so it can't spread to other plants. Pick up any plant debris around the area so it can't spread. Then I'd treat with a systemic fungicide. If it persists dig it out and don't plant anything there for a couple of years. Try not to wet the foliage of your plants when watering