Orange oil is effective in killing ants, both inside and outside the house. The oil's main ingredient, D-Limonene, is an extract from the citrus peel. This extract kills the ants by destroying the wax coating of the insect's respiratory system.
Orange oil can be used to kill the fire ants that are building colonies in your yard. According to the Urban Harvest website, "recent studies have discovered that orange oil solutions are effective in decimating fire ant colonies and, if the solution reaches the queen, destroying the mound for good." To kill the ants, pour enough orange oil or an orange-oil solution over the ant bed, completely soaking it. Do this procedure when you notice the ants are in the mound and not crawling about searching for food.
Indoor ants can be effectively eliminated with orange oil or an orange-oil solution. The benefit of using orange oil to kill ants in the house is that it is non-toxic to humans and has a pleasant scent. Either purchase or make your own orange oil solution and put it in a spray bottle. Spray the ants and all surfaces they are crawling on. Find the area in which the ants are entering the house and spray it with the oil. This will create a barrier that lasts for up to 24 hours. Orange oil is rather strong, so it also can be used as a cleaning agent. If you are using it to kill ants in your kitchen, go ahead and clean your countertops while you are at it. The scent will also deter the ants from returning.
How It's Made
Orange oil can be purchased or you can make it on your own. The Orkin website suggests you simmer orange peels and collect the condensation. This is the oil you will use. Another way to create the orange oil is by filling a container with the citrus peelings and cover them with water. Let them sit for a couple of days and then strain off the liquid for your oil. The Urban Harvest website suggests that molasses or compost tea may enhance the effect of orange oil on fire ant mounds. A simple way to create a fire ant solution is by mixing 6 oz of orange oil, 1 tablespoon blackstrap molasses, a squeeze of liquid dish soap and water in a gallon jug.