TIMMY STRIKES AGAIN

My neighbour's cat, Timmy likes to trespass into my porch and urinate everywhere. My friend Daniel told me to place mothballs as a preventive measure. For a whole week, there was no smell of ammonia and I thought my troubles were over.
Tada, I got a whiff of the urine the moment I reached home yesterday afternoon. The mothballs are not working. Timmy sprayed all over my porch again. You can see the guilty fella resting under my plant rack.