How to Kill Harvester Ants

Around 1/5 to 1/4 inch long -- 5 to 6 millimeters -- harvester ants come in many colors, including red-brown, black and yellow. They are one of the few types of ants that sting. If you see harvester ants in your garden, you have several options for eradicating them and protecting you, your family and your pets from their painful bites.

Eliminating harvester ants begins with eliminating anything that attracts these ants in the first place. A tidy yard is more likely to be a pest-free yard. Example areas to focus on include:

Fixing plumbing, such as leaking garden faucets or dripping sprinklers. Ants are drawn to convenient sources of water.

Putting away pet food dishes, picking up fallen produce and clearing away any other sources of food.

Picking up and putting away old garden equipment, piles of organic debris and other sources of ant shelter.

Moving mulch, plants and grass 1 foot away from the foundations of garden sheds and other structures. Ants tend to be attracted to these areas. 

Boiling water burns and kills harvester ants on contact. The water also collapses and drowns the underground ant nest, making this a potent and all-natural method for controlling ants.

For the best results, use 3 to 4 gallons of boiling water. Pour the water directly on the harvester ant nest, soaking the nest and the surrounding soil with hot water.

Sometimes, the first application of boiling water doesn't fully wipe out the harvest ant nest. It may take three or four applications of boiling water before all ant activity stops.

Handle boiling water carefully to avoid scalding yourself. Don't forget that the resulting steam can also scald you. Wear gloves, closed-toe shoes and long pants when pouring the hot water on the ground to keep from getting scalded by hot water splashing off of the soil. Make sure you have no obstacles in your way as you carry the water to the nest.

Diatomaceous earth, a fine, white powder is made from crushed, fossilized diatoms, and is a natural way to control pests. The powder has microscopic sharp edges that cut and kill insects, including harvester ants. Use a food-grade DE, rather than one made for pool filters.

Uses for diatomaceous earth against harvester ants include:

Sprinkling the powder around the plants you want to protect from ants. Create a circle of diatomaceous earth around the base of each plant.

Dusting plants, patios and other surfaces with diatomaceous earth.

Scattering a thin layer of diatomaceous earth on and around a harvester ant nest.

Apply diatomaceous earth again after it rains, as rain and watering plants wash away the fine powder.

Do not inhale or ingest diatomaceous earth. It will irritate your mouth, eyes, nose and lungs.

Made from natural minerals, boric acid works as a low-toxic insecticide against harvester ants and other pests. It kills ants by dehydrating and starving them once they eat it. While you can buy boric acid-infused ant baits in garden stores and home improvement centers, make your own ant bait at home using common kitchen ingredients.

Strips of sturdy cardboard

Honey

Peanut butter

Boric acid 

Measuring spoons

Mixing bowl

Learn what type of bait will attract the harvester ants in your yard. Smear peanut butter onto a strip of cardboard and honey onto another strip of cardboard, then place the two strips near the harvester ant nest.

Check the cardboard baits over the course of a couple of days. The strip that draws the most harvester ants is the bait to use.

Add 3/4 teaspoon of boric acid into a mixing bowl.

Mix in 3 ounces of honey or 2 ounces of peanut butter.

Stir until the boric acid is mixed evenly throughout the bait.

Place the bait near the harvester ant nest, smearing it onto cardboard. The ants will feed on the bait and take it back to their nest where the boric acid will eliminate the entire harvester ant colony.