Whiteflies

Whiteflies are small, piercing-sucking insects, 1 to 3 mm (0.04 to 0.12 in) long, that feed on sap, mainly under leaves, and fly up in a cloud when you shake the plant. The whitefly treatment describes a method intended to break their life cycle.

By sucking sap, they weaken the plant and excrete sticky honeydew that encourages sooty mold, a black fungus. An untreated infestation causes yellowing and leaf drop and slows growth.

Signs to check

• A cloud of white insects, 1-3 mm (0.04-0.12 in) long, flies up when you shake the plant.
• Oval, immobile larvae or eggs under the leaves.
• Leaves feel sticky from honeydew.
• A black, sootlike coating (sooty mold) appears on the leaves.

What you may notice

• Black coating (sooty mold) · A dry, powdery black coating resembling soot forms on leaves and stems.

What to do now

Whitefly treatment

1. Isolate the infested plant immediately to keep whiteflies from spreading to others.
2. Shower your plant. Use a stream of lukewarm water to rinse the leaf undersides thoroughly and dislodge as many adults and larvae as possible.
3. The French source gives this black-soap solution: mix 1 to 2 tablespoons of liquid black soap into 1 liter (1.06 US qt) of lukewarm water. The spoon size is not specified.
4. The source then calls for spraying the solution generously over the whole plant, especially under every leaf, where larvae and eggs hide.
5. Place yellow sticky traps near the plant. The color attracts flying adults and helps reduce their population.
6. The source calls for repeating the black-soap spray every 5 to 7 days for at least 3 to 4 weeks, with the stated aim of breaking the reproductive cycle and removing newly hatched insects.

Prevention

• Inspect the undersides of every new plant's leaves carefully before bringing it into your home.
• Quarantine new plants for 2 to 3 weeks.
• Check your plants once a week for early signs.
• Keep air circulating around your plants; whiteflies favor enclosed, poorly ventilated conditions.