Whiteflies infest both indoor and outdoor plants and spread easily from plant to plant. Whiteflies share ancestry with aphids, mealybugs and scale. These insects usually attach themselves to the underside of leaves and feed by sucking the sap from the plant. Most active in warm climates, whiteflies pose a serious threat to plants if left unchecked either outdoors or in greenhouses. Rid your plants of whiteflies through natural or chemical means.
Recognise whiteflies by their appearance. Adults grow to about 1/16-inch long and resemble tiny moths. They feature four broad wings and hold them over the top of the body. The delicate wings are covered with a powdery white wax. Inspect plants frequently for any sign of whitefly infestation. Remove any plants that appear heavily infested and don't allow them to come in contact with healthy plants. Isolate any new plants for several days and observe them for whitefly presence before introducing them into an area with other plants. Plants infested wtih whiteflies often exhibit yellowish leaves
Use biological control methods. Whiteflies have many natural enemies, including ladybirds, lacewings and spiders. Introduce these predators into the garden or greenhouse to control whiteflies. However, this method may prove somewhat ineffective since the widespread use of pesticides controls these insect populations.
Trap the insects using a homemade trap. Paint both sides of a 12-inch by 16-inch strip of cardboard or strong poster board with yellow paint. Allow the paint to dry and then coat the strip with petroleum jelly or another sticky substance. Hang the trap vertically or suspend it horizontally just above the plants using stakes. Whiteflies are attracted to the colour and become trapped.
You can also buy whitefly traps at many home and garden stores. The University of Missouri Extension recommends the installation of one trap for every two plants.
Vacuum whiteflies off plants using a small, handheld vacuum. Take action early in the morning when the temperature is cooler and whiteflies move more slowly. Place the vacuum bag containing the insects inside a freezer for 24 hours to kill the insects. This method is most effective in an early infestation when few eggs have been laid.
Apply insecticide to the underside of leaves to eradicate whiteflies. Since whiteflies have developed a resistance to many chemicals, several applications may be needed to successfully control the insects. Reapply the insecticide at 5- to 7-day intervals.
Buy these insecticides over the counter under such names as insecticidal soap, pyrethrins, permethrin, imidacloprid, malathion and neem oil. Reduce the opportunity for chemical resistance by alternating the types of insecticides you use.
Follow label directions when using insecticides.