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University of Illinois Extension

Whitefly

Whitefly and nymphs

Whitefly and nymphs  

Frequency

2 (1 = rare 5 = annual)  

Severity

3 (1 = very little damage 5 = plants killed)  

Hosts

Numerous indoor plants as well as several annuals, perennials and vegetables.    

Symptoms

Severe infestation may cause plant damage such as mottling and yellowing of leaves as well as a reduction of vegetable yields. Whitefly (covered by a white waxy powder) adults are small "dandruff" size insects. When plants are disturbed, the whiteflies flutter around the plant and soon return to the plant to continue feeding.  

Life Cycle

Whitefly species that are damaging to cultivated plants are not cold hardy in Illinois. To survive our winter they must be on plants indoors (house plants, herbs and greenhouse crops). The insects (usually in the egg stage when they are difficult to see) are often shipped north on flower and vegetable transplants grown in the south. The insects tend to feed mostly on the lower side of the leaves. Eggs are primarily laid on the upper leaves of the plant, but the clear, tiny, oval nymphs occur primarily on the lower leaves.  

Management

On indoor plants one can try using yellow sticky traps to capture the adults. These work much better if the foliage is disturbed daily, causing the whiteflies to fly off of the plant. Infestations can also be reduced by discarding heavily infested plants. Outdoors, use suggested insecticides according to all label directions and precautions. Insecticidal soap, summer oil, and chemical insecticides are effective. On vegetables, be sure to follow the recommended time interval between treating the plants and harvesting the crop. If there is no pre-harvest interval,DO NOT use that insecticide on the food crop.


Filed under plants: Vegetables

Filed under problems: Insects Damage

More information is available on Hort Answers.