Fly and Spider eradiciation

I just bought a house near Lake Pontchartrain and seem to have more flies and spiders than I have had at others houses I've lived at in Metairie. I don't know if there is any correlation with the location of the lake and flies/spiders, but I want them gone.

I've had a family pest control friend start spraying the house and exterior but it hasn't got rid of all the spiders. We also have a cat lady next door to us and they crap on my lawn so I suspect her cats and their crap are contributing to the flies. I am resolving the cat problem with a scarecrow sprinkler so its helping with them being on my lawn but the flies are still around.

For the flies, I've seen apple cider vinegar in a jar with a funnel, i've seen sugar water, etc.

For the spiders, I was going to try citronella or tea tree oil in water or salt water and spray the foundation of the house.

My question is, has any of the methods I want to try worked for anyone? If not, what worked the best?

And no, I'm not burning my house down or any other fire methods commonly thrown out by the arachnophobist on this board.