Whiteflies: how to spot and manage them safely

Whiteflies are tiny, moth-like insects about the size of a grain of rice. They gather on the underside of leaves and fly up in a little cloud when you brush the plant. Silverleaf whitefly is the common one here.

How to spot them:

1. A cloud of tiny white insects rising when you disturb a plant.
2. Yellowing, wilting leaves and slowed growth.
3. Sticky honeydew on lower leaves, often with black sooty mould on top of it.
4. Clusters of pale scales and eggs on the underside of leaves.

The damage they do: whiteflies suck sap and weaken plants, and the honeydew and sooty mould block light from the leaves. Heavy numbers can make plants more prone to other problems.

How to manage them, safely:

1. Hang yellow sticky traps. Whiteflies are drawn to yellow, so traps both catch adults and tell you how bad it is.
2. Hose the underside of leaves to knock off adults, eggs and honeydew.
3. Prune and bin badly affected leaves.
4. Encourage predators such as ladybirds and lacewings (companion planting helps).
5. Try insecticidal soap or neem oil if needed. Spray the underside of the leaves in the cool of the day, and repeat every few days, as whiteflies breed quickly.

We do not recommend harsh synthetic sprays for whiteflies on food plants. Whiteflies build up resistance to them quickly, while the gentle options stay effective. For the full picture, see our guide to managing pests safely.

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Image: CSIRO, CC BY 3.0, via Wikimedia Commons.