Apply insecticide soap, mixing 1-teaspoon mild soap with 1 quart of water in a spray bottle. Spray the mixture on the leaves of the lemon tree and on all of the growing surfaces. Coat the trunk in the soap. Apply every 7 to 10 days until the ants are gone. Remove mulch from near the tree trunk. A moat area should be present between the mulch and the tree trunk, preventing the mulch from touching the bark of the tree.
About this Author
Christina Wheeler has been a professional freelance writer since 2007. She lends her expertise in animal care, gardening and home improvement to online publications such as Garden Guides and eHow. Wheeler studied business management at Ohio University.