Not sure if this will help but it has worked for us in the past for a slightly different need-
We seasonal camped for a few years and left our trailer on the heavily wooded site year round. Other campers told us that the smell of mothballs and downy dryer sheets would repel critters. So in the trailer, in every nook and cranny that I could find to stuff them in I used the dryer sheets. Was a nice smell for when we opened it up too. Never in the 6 years that we owned that trailer did we find evidence of mice, etc inside.
Also on the site we had a shed. Critters galor inside of it every weekend when we opened the door. So I took some old nylons, stuffed them full of mothballs, and hung them on nails that I put in on the framing for the floorboards. When we opened the doors we did get a whiff of mothballs but not too overpowering, and it dissapated quickly. In the fall when we closed up for the winter I also put some inside the shed. Once in awhile I'd find evidence of mice, etc. but not the crowds we once had.
Maybe you could adapt this idea for your problem? Good luck and I hope you get to enjoy your patio.
