How do I control whiteflies on houseplants?

Question: 

How do I control whiteflies on houseplants?

Answer: 

Whiteflies are common insect pests of hibiscus, poinsettia, chrysanthemum, and a number of other indoor plants.  They are most often noticed when watering or handling a plant.  When disturbed, whiteflies flutter about the plant for a short time before returning to the plant. 

Whitefly adults are tiny, white, moth-like insects.  Female adults lay eggs on the undersides of the plant’s foliage.  After 5 to 7 days, the eggs hatch into tiny, pale green, immatures called nymphs.  The nymphs crawl a short distance before settling down to feed for 2 to 3 weeks.  After feeding for 2 to 3 weeks, the nymphs progress to a nonfeeding stage and then finally to the adult stage. 

The nymph and adult stages of whiteflies feed by inserting their short, needle-like beaks into foliage and sucking out plant sap.  Heavy whitefly infestations often cause stunting or yellow of leaves, leaf drop, and a decline in plant health. 

Whiteflies on houseplants are extremely difficult to control.  Prevention is the best management strategy.  Carefully check newly purchased plants and plants brought indoors from the garden or patio in the fall.  Indoors, isolate these plants from other houseplants.  Frequently check the new arrivals.  Begin control measures at the first sign of a whitefly infestation.  One way to reduce the whitefly population on an infested plant is to wash the undersides of the leaves with a moist cloth or sponge.  Unfortunately, washing is labor intensive and only practical for small plants.  Insecticides are another control option.  Insecticides must be applied uniformly and frequently (at weekly intervals) to the undersides of the plant’s foliage.  Apply insecticides specifically labeled for use on houseplants.  Carefully read and follow label directions.  It’s usually best to discard heavily infested plants to prevent the whiteflies from spreading to other indoor plants.

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