Whitefly

Symptoms by part

Causes

• Warm, sheltered environments with poor air circulation.
• High humidity combined with stagnant air.
• Introducing new, infested plants into an existing collection.

Could be confused with

• Aphids · Aphids are usually larger, wingless in their early stages, and do not fly up in a cloud when the plant is disturbed.
• Mealybugs · Mealybugs look like small, fuzzy white cotton tufts rather than tiny moth like insects.

Treatment

1. Gently shake the plant to disturb the adults, then use a handheld vacuum to capture them as they fly.
2. Spray the undersides of all leaves thoroughly with a strong stream of water to dislodge nymphs and eggs.
3. Apply fatty acids to the undersides of the leaves every 5 to 7 days to coat and suffocate the insects.
4. Use pyrethrins as a final option if the infestation persists, ensuring you cover all leaf surfaces.

Without chemicals

• Prune away and dispose of heavily infested leaves to reduce the population.
• Isolate affected plants immediately to prevent the insects from moving to healthy neighbors.
• Increase air circulation around the plants using a small fan.

Chemical options

• Fatty acids, spray directly onto the insects on the undersides of leaves, follow the label.
• Pyrethrins, apply to the undersides of leaves where insects congregate, follow the label.

Preventing it

• Inspect new plants thoroughly for signs of insects before bringing them near your collection.
• Keep plants spaced out to ensure good airflow.
• Wipe down leaves occasionally with a damp cloth to remove dust and potential eggs.

When to act

Act as soon as you see the first white insects flying around your plants. If the plant is severely stunted or covered in black mold that does not wash off, it is often best to remove the plant entirely to protect the rest of your collection.

Questions people ask

Will whiteflies kill my plant?

While they rarely kill a plant quickly, a heavy infestation will severely weaken it, making it susceptible to other issues.

Why do my leaves look black?

That is likely sooty mold, a fungus that grows on the sticky honeydew left behind by the whiteflies.

Can I just wash them off?

Washing helps, but because whiteflies reproduce quickly, you usually need to combine water sprays with other treatments to get them under control.

Plants it affects

• Browallia
• Chenille plant
• Chinese hibiscus
• Coleus
• Fuchsia
• Gardenia
• Lantana
• Lion's Ear
• Night blooming jasmine
• Poinsettia