Good thread,
I have mosquitos here and have been looking at some none chemical ways to reduce and have heard that the propane traps work well. I guess the propane attracts them them the same as our breath and then the get stuck in a trap. THese traps can be kinda spendy and they do burn up the propane, but once you break the life cycle the population is reduced, so you can let up.
The poor boy version is to remove standing water as has been mentioned and then take 5 gallon buckets with water and grass clipping in them and put them every 50 ft or so around the area. Let the water stagnate and then every week or so check to see if there are eggs in there and if so take really fine wire mesh and pour the water in the buckets through it onto the ground on hot sunny days. The mesh and the sun kill the larvae.
MOsquitos don't travel very far and they have short life cycles, so if you can kill the larvae you won't have many mosquitos after a few weeks.