An ounce of prevention is worth a pound of cure. I'm new to chickens, but having had a house in Dallas in the early 80's, in a part of it where many people had kept many dogs for many years, I'm not new to bug blocking.
-------------------------------------------
I painted every interior surface of my coop when I built it, except the nest boxes I think. (will have to look when I go out later. 2 coats of Kilz2 latex. (I really hate bugs, especially the ones I can't see.)
And get some agricultural dusting sulfur, and sulfur your fenceline, focusing on your border with the neighbor's birds. Snakes won't cross it, ticks and fleas don't like it, I don't think ticks will cross it. most bugs just hate the stuff. I use it more for snakes around here than anything else. Non toxic. You can do a world of good with a visible one inch line of powder.
Then get everybody else's advice for the birds themselves.
I use old shovel handles for perches - the hardwood ones will take orange oil, nothing can penetrate the nylon ones. And while I've used Sevin dust, I've switched to DE because I also keep fish and bees.
But Sulfur on the fencelines is just the best, and nice bright white paint. I did the inside of my greenhouse coop with it too, right away. Before any critters could move in. For a yard pesticide I use beneficial nematodes. Applied at the right temp, the critters just keep eating bugs as long as the yard is moist enough for them to live in.
Gypsi