A good yard spray specially formulated to deter mosquitoes is Mosquito Barrier. Mosquito Barrier is a liquid garlic-based spray that contains sulfur, a natural repellent. Garlic juice is highly toxic to mosquitoes but does not harm plants, people, pets, bees or butterflies.
The strong odor of garlic juice is undetectable to humans but drives mosquitoes away because of their ability to detect scent that is 10,000 times greater than that of a human. Mosquitoes avoid areas that have been sprayed with garlic juice for up to one month or longer. Mosquito Barrier also contains canola oil that coats standing water where mosquitoes breed, suffocating their larvae. This repellent is also effective against ticks, gnats and fleas.
Mosquitoes lay their eggs in standing or stagnant water. Hundreds of thousands of mosquitoes are born each day. They rarely travel more than 300 feet from their breeding ground.