I've actually been having some pretty good luck recently using a light and a body of water to catch queens. If you guys have a pool or spa with a submerged light source, or a floaty pool and a waterproof light source, wait until it's starting to get dark and turn the light source on. Come back in about 10 - 20 minutes and you'll usually find some queens in there, especially if it rained during the morning.
I've been catching queens of species I've never even seen before, such as Pheidole. Be sure to give it a try!
