Soap-and-oil spray is the easiest homemade spray to make and is very effective for controlling a wide range of pests.
Start by mixing a concentrate solution to keep on hand by combining 1 cup/.24 L of vegetable oil and 1 tablespoon/14.8 ml of liquid dish soap. To dilute this mixture to use in your garden, combine 2 teaspoons/9.86 ml of the concentrate with 1 cup/.24L of water. Put the mixture in a hand sprayer and spray it on infested plants. Be sure to wet both tops and undersides of leaves.
