Pesky Whiteflies

Prevention
The best way to prevent any insect infestation, including whiteflies, is to grow healthy plants. Research shows that pests actually seek out stressed plants for attack. Since many plants are stressed from the effort to survive our summer heat, they become prime targets for pests. Whiteflies are also fond of large-leafed plants such as squash, melons and pumpkins.

Make sure all plants are getting enough moisture. Water for annuals should penetrate about a foot deep, two feet deep for shrubs, and three feet for trees. Monitor your plants regularly, looking for signs of stress such as yellowing, wrinkled, or dropped leaves. Learn to recognize the difference between beneficial insects and pests.

Monitoring
Whiteflies leave pinprick-sized yellow spots where they suck plant juices. If their numbers are high, tapping a branch will flush them out where you can see them. Look on the undersides of leaves where the tiny, round, immature scale form of this insect is attached to the plant tissue.

Controlling
There's really no chemical pesticide that is effective against whiteflies. Your best bet is to start spraying them off plants with a forceful blast of water from the hose as soon as you see signs of these pesky pests. You may need to do this daily. If the problem continues, add one to three teaspoons of liquid dish soap to a gallon of water to make a soapy water spray. Spray early in the morning to lessen the chance of sunburn.

Sticky Traps
Sticky traps are pieces of yellow cardboard covered with a gooey substance. They're like flypaper for garden pests, and are a good tool for monitoring for whiteflies. You may even catch enough adult flies to achieve control of the pest. You can buy sticky traps, or make your own with yellow plastic or cardboard coated with petroleum jelly. Hang the traps close to the tops of plants.

Photography by Cathy Cromell/NationalGardening.com

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