Whiteflies

Photo:  Dr. Arnold H. Hara, CTAHR

Problem

The plants have tiny white flies all over them. The undersides of the leaves are white and some of the leaves have a black, sooty looking film.

Description

Giant Whiteflies and Spiraling Whiteflies both lay eggs in a spiraling pattern on the underside of the plant leaves. With Whitefly infestation, you may see the spiraling pattern of eggs, the oval shaped nymphs, as well as adults all on the same plant. Adults look like tiny white moths. Giant Whiteflies have brown markings on their wings. Nymphs produce a white, waxy filament-like material. Whiteflies feed with sucking mouthparts and excrete a sticky substance called honeydew which leads to growth of sooty mold.

Information

• HDOA – New Pest Advisory Giant Whitefly
• CTAHR – Crop Knowledge Master – Pest - Whitefly
• Whiteflies: Quick Tips (UC Davis IPM)

Control

Wash whiteflies off the plant with a strong spray of water. When plant is dry, apply insecticidal soap to the underside of the leaves. The spray must contact the nymphs and adults to be effective. You will need to repeat the application 3-4 times in order to kill all stages of the pest. Avoid broad spectrum insecticides because they will kill parasitic wasps and other natural enemies.

If the infestation is heavy, prune the plant back heavily and throw away infested foliage in sealed bags. Keep an eye on the plant for re-infestation and spray with insecticidal soap as needed.

You can try using yellow sticky cards if the infestation is light. Whiteflies are attracted to the color yellow and will stick to the card. Or try laying aluminum foil at the base of the plant which repels the pest. Use foil with caution however; on sunny days foil can reflect the sunlight and “cook” fruit on affected plants.

Ants will “farm” whiteflies, feeding off of the honeydew they excrete, so you must control the ants if you want to get rid of whiteflies.

Photo: Dr. Arnold H. Hara, CTAHR

Kendal Lyon, Hawaii Island Master Gardeners