Stagnant water, which provides a breeding ground for mosquitoes, is the major source of mosquito problems around the home. Some obvious sources of stagnant water include neglected birdbaths, wheelbarrows, tires and children's pools which accumulate rainwater. Water may also puddle around plants when you irrigate your yard. If you have problems with mosquitoes breeding around the home, you can control them with coffee grounds. Coffee grounds will kill mosquito larvae while providing beneficial nitrogen to garden plants.
Collect coffee grounds in a jar and allow them to age for at least 25 days. Aged coffee is more effective at killing larvae than fresh coffee.
Sprinkle coffee grounds around garden plants and trees where water accumulates to prevent mosquito larvae from thriving in stagnant water.
Add 3 tablespoons of coffee grounds per 1 cup of stagnant water in vessels around your home to kill active mosquito larvae. Do not add the coffee to ponds or other bodies of water where animals thrive.