A good solid capsize or two ought to fix your problem, and you'd get a BFS out of it to boot!
I second the wasp traps and love the idea of hoisting one up to where they go in as well. As for moth balls I HATE the smell of those things and the smell does linger. Be sure you're okay with that because if you drop a couple in the mast you might end up with a boat that smells like moth balls.
Premethrin is what most bug spray is these days and they saturate baby's mosquito nets in the stuff in Africa. It's very safe for humans, is wickedly toxic to cats and I have no idea how it is for ropes, sails and canvas.
I'd try the traps and moth balls if you can stand them.
I'll give it a try. Mast is deck stepped so no problem there. I'll look into the premethrin.