swarm trap questions

[Bees&Wood]

I'm planning on trying to make a swarm trap for next spring, since I've had 2 wild swarms try to move into one of my hives in the last 3 weeks. I've read to put drawn comb and lemongrass oil lure in the trap. So my question is, if you put drawn comb in the trap and leave it sitting out, how do you keep from getting wax moths?? Thanks

[Walliebee]

Bt. (bacillus thuringiensis) Do a search on this site for good info.