How to Control Whiteflies on Outdoor Plants

Whiteflies are minute insects with piercing and sucking mouth parts that suck plant juices. They hide in huge numbers on the undersides of leaves, flying out in great clouds when disturbed. They're common on citrus, greenhouse and foliage plants.

Things You'll Need

• Parasitic Wasps
• Tanglefoot Pest Barriers
• Garden Hoses
• Garden-hose Nozzles
• Pyrethrin
• Vacuum Cleaners
• Insecticidal Soaps
• Colored Paper
• Paper And Binder Clips
• Vacuum cleaners

Instructions

1. Look at the undersides of leaves on plants suspected of having a whitefly infestation. Plants will appear weak, and black sooty mold fungus may be evident on stems and leaves. Whiteflies also swarm above plants in huge masses on sunny days.

2. Wash all parts of infested plants, including the undersides of the leaves, with a strong jet of fresh water.

3. Hang sticky traps near infested plants. Sticky traps are yellow in color to attract the insect, and coated with a sticky substance to trap and catch them when they land to investigate. You can make your own sticky traps with Tanglefoot pest barrier spread on yellow paper. Hang the homemade traps near infested plants using bent paper clips.

4. Vacuum adult whiteflies from leaves on plants with mild infestations. This method also works well for indoor plants infested with whitefly.

5. Release parasitic wasps (Encarsia formosa) to control whiteflies in a greenhouse.

6. Spray insecticidal soap when whiteflies are resting - early morning or late afternoon is best.

7. Spray with pyrethrin. Pyrethrin is an organic pesticide made from chrysanthemums. There are also chemical controls for whiteflies.

Tips & Warnings

• Always try the least toxic method of pest control as your first step.

• Select and grow plants that are naturally resistant to whiteflies. These include plants with a milky sap and thick or fuzzy leaves; the particular plants will vary depending on where you live.

• Plants native to your area are generally naturally resistant to insect attack.

• Hummingbirds eat whiteflies. Encourage them to visit your garden by hanging a feeder and keeping it clean and full.

• When whiteflies feed, they secrete a sticky sap called honeydew, which allows sooty mold, a fungal disease, to form. Whiteflies also spread viral diseases between plants.

• If you use pesticides in your garden, you'll kill natural predators of whiteflies, such as the whitefly predatory beetle and the whitefly parasite.

• If you choose a chemical control, always wear protective clothing and safety gear, including a long-sleeved shirt, long pants, neoprene gloves, goggles and a respirator.