Whiteflies are tiny pests that can cause considerable damage to plants by feeding on their juices and passing along viruses. There are more than 150 species of the insect, with three commonly found in home gardens. Gardeners can control whiteflies with cultural, mechanical, biological or chemical means. Controlling whiteflies with homemade sprays may present gardeners with the best defence, as the pest has shown growing resistance to many insecticides. Also, using traditional insecticides also kills off the beneficial insects that control whitefly populations.
Wormwood spray is effective against a number of gardening pests, including flies. The spray can be made by placing a generous amount of woodworm leaves in a pot and covered with boiling water. Allow it to steep for three hours. After it cools, dilute 1 part of the leaves to 4 parts water. Spray as needed.
The active ingredient in pyrethrum spray kills whiteflies by attacking the nervous system. Pyrethrum is a flowering plant that, when used to make homemade sprays, is best grown from seed. Pyrethrum is present in the immature seed. Dry the seeds and grind them into a fine powder with a pestle and mortar. Combine 10 grams of the powder to 3 litres of water. Allow it to sit in a dark room for three hours. Mix 1 tsp of dishwashing liquid to the mixture before use.
Dishwashing Soap Spray
Gardens Alive shares a homemade spray released by U.S. Department of Agriculture researches found to be effective at getting rid of whiteflies. Combine 1 tbsp dishwashing liquid with 1 cup vegetable oil and shake well. Dlute this mixture by adding 2 tbsp of the dishwashing mixture to 1 cup water. Store and apply the solution in a spray bottle.
All-Purpose Insecticide Spray
To test the waters with a homemade spray without going through added expense, try this all-purpose insecticide spray made with just two ingredients. Combine 1 qt. liquid soap with ½ cup rubbing alcohol. Mix the ingredients directly in a spray bottle. Avoid applying in direct sunlight to prevent leaf damage.