Grow Mint. It's not only a great herb, but also a natural pesticide, and using natural pesticides whenever possible means less chemicals to harm the earth. Pinch and crush a few mint leaves and place under cabinets and around doors where ants might enter. Other natural pesticides: A thin amount of lemon juice along door jambs will keep out ants also. Garlic or Cayenne Pepper sprinkled on plants keeps aphids at bay.