[header] How to prevent mosquitoes from breeding [title] Empty, drain, or cover all things that can and may hold standing water. [step] Areas of your backyard or porch may have spots where rainwater can pool. Barrels and trash cans tend to collect rainwater extremely well. 
Old tires, empty bottles, buckets, and other small containers can condense water vapor into tiny pools. Empty and drain all pools of water and cover them up to prevent more water from gathering.