Where is it kept?
I read on another forum I think, about the benifits of using steel post for stands. Reason being, bugs don't climb steel as redily as wood, or bricks/concrete.
I beleive steel gets too hot for them, and they don't like the texture, you could keep it oiled too. They likely wont get past an oil slick.
If you can keep it isolated enough from other trees, this may help.
Also, I never spray. I only use bug on bug defense. Centipedes for soil pests. Jumping spiders (active hunters, not web waiters). Any spiders. Ladybugs. Lacewings. Praying manti.
There is a product called predalure that lures predator bugs. I may try that next year.
I read bought ladybugs bring parasites that kill local ladybugs. A no-no.
You can pluck spider egg sacks out of webs and let them hatch in your tree. I found about a hundred mite size baby spiders in a portopotty the other day. I am considering collecting them all.
Hard hose spray every day could work too. They wont get hold.
Good luck!
Sorce