It can help reduce the population, but will not eliminate mosquitoes. Mosquitoes use water to lay eggs and spend their pre-adult time growing within the water, so removing containers, bird baths, mud puddles, and other spaces that hold water will make your yard less attractive. However, even a space as small as a leaf can be enough to hold eggs, and nearby properties can also be attracting mosquitoes to the area, so it is unlikely to eliminate mosquitoes completely.