Agricultural lime is formed from limestone. It contains high amounts of calcium and magnesium carbonate. Because of this, lime is applied to soils with low pH levels to make them more basic. Lime powder is also used as a natural insecticide. Insects' bodies dry out and they suffocate when they come into direct contact with lime.

Use lime to repel garden insects and fleas.

Flea Repellant

Use lime in your landscape to repel fleas and keep your pets from catching fleas when outdoors. Identify any moist areas in your yard that may house fleas. Clear these areas of dead leaves, branches, weeds and other debris. Spread a layer of agricultural lime over these areas and rake it into the soil. As the lime comes in contact with fleas that are present or try to move in, it will dry out their bodies and kill them. Apply a light dusting of lime over lawns just after mowing to keep fleas from taking up residence.

Garden Pest Repellent

Use lime as an insect repellent in your flower and vegetable gardens. Mix lime powder with an equal amount of wood ash and pour the mixture in a small ring around your plants that are the most susceptible to pests. The ring of lime will prevent ground-traveling pests from reaching your plant. Any insects that walk through the lime will be suffocated by the powder. This method can be used against slugs, potato beetles, corn rootworm and cabbage maggot.

Insecticidal Spray

Create a homemade insecticide spray using lime to spot treat infect plants both outdoors and indoors. This spray is especially effective against spidermites. Add 1/4 to 1/2 cup of agricultural lime to 1 gallon of water. Mix in 2-3 tablespoons of insecticidal soap. Stir the solution to mix and pour it into a spray bottle. Label the bottle to avoid using the contents by mistake. Spray a leaf of the infected plant with the solution and wait a few days to see if there is any damage. If not, spray the infected areas of the plants, targeting the visible insects. Reapply the insecticide after rain or windy weather.


Use caution when applying lime to soil or plants. Lime is applied to soil and lawns to raise the pH of the soil making it more basic. If lime is applied in large amounts or over a long period of time, the soil in your garden may develop a pH so high that the growth and development of plants will be stunted. Incorporate your use of lime as an insect repellent with other methods to avoid over use. Test your soil often when using lime to monitor its pH level.