Whiteflies

Description:
Whitefly infestations are easy to diagnose because they fly up in swarms when disturbed, creating a cloud of white over the infected plant(s). Up close, whitefly look like tiny white moths. Like many other plant feeding insects, whitefly excrete honeydew which, in turn, attracts sooty mold and ants. Greenhouses provide the perfect conditions for whitefly population explosions. They thrive in warm, still air and are most active outdoors during the heat of the day, especially in the summer.

Damage:
Whiteflies feed from the undersides of leaves and severe damage can cause the leaves to curl up and die. In the early stages the leaves will appear speckled.

Prevention:
The first step of prevention is to avoid introducing whiteflies into your garden. Carefully examine plants before you purchase them. Run your hands through the foliage, if a cloud of whiteflies jump out do not buy the plant. Also, check the undersides of the leaves. Whitefly eggs and nymphs stay on the undersides of leaves. They are almost clear and sooty mold will usually be present around them on the honeydew. Just to be on the safe side spray all plants you purchase with insecticidal soap or horticulture oil, before you plant them in the landscape, to kill any eggs or nymphs. Be certain to spray the undersides of the leaves.

Management:
Mild Infestations: Remove and destroy infected leaves and wash the plant down with soapy water. Whiteflies are attracted to the color yellow and can be trapped on yellow sticky cards. You can buy traps or make you own using yellow posterboard coated with petroleum jelly.

Severe Infestations: Azadirachtin (Neem), malathion, or resmethrin are effective pesticides just be sure to spray the undersides of leaves. Whiteflies may quickly become resistant to a pesticide if it is used repeatedly. Alternate classes of insecticides to prevent the development of resistance. Resistance to soaps and oils is unlikely to ever develop, so these materials should be used as much as possible.