There are several ways to kill ants outside, including:
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Diatomaceous earth: Sprinkle food-grade diatomaceous earth (DE) along ant trails. DE kills ants through dehydration. It affects only those ants that come into contact with it. Spread the DE around the ant nest as well as any trails you see in your yard. For preventative measures, sprinkle it around the perimeter of your house to keep ants outside. Diatomaceous earth dries the liquids inside the ants and kills them within a few days or weeks.
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Boiling water: Pour boiling water directly into the anthill to kill the colony. Boiling water does kill vegetation, so be careful using this method on lawns.
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Soapy water: Make a spray of 1/4-cup Castile liquid soap and 1 quart of water. This spray kills ants on contact. Its effective against scout ants but won’t kill ants back in the nest. Spray soapy water directly on any ants you see outside the nest to kill them on contact. Pour the solution into anthills in your yard (or indoor ant nests, if possible) to kill the ants remaining underground. Soapy water will only kill ants it comes in direct contact with, and it has no lasting residual effects.
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Pepper: Sprinkle black pepper or cayenne pepper on an ant trail and down an anthill. When ants ingest the pepper, they suffocate and die.
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Mint tea: Used mint tea can be poured into ant nests to kill them.
It's important to note that some home remedies, such as cornmeal, do not work well for killing ants. Additionally, purchasing both sugar baits and baits that contain grease and protein will allow you to kill a wider range of ants outdoors.
