Aphids: how to spot them and manage them safely

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Aphids are tiny, soft, sap-sucking insects, usually green but sometimes black, brown or yellow. You will often find them clustered on new growth and on the underside of leaves.

Also known as: greenfly, blackfly, plant lice.

How do I spot them?

1. Small, pear-shaped insects massed on stems and the backs of leaves.
2. Curled, distorted or yellowing leaves.
3. A sticky, shiny residue (honeydew) on leaves, sometimes with black sooty mould growing on it.
4. Ants marching up and down the plant. Ants farm aphids for their honeydew, so they are a giveaway.

What damage do they do?

Aphids weaken plants by drinking their sap, which can stunt growth and spread plant viruses. A small number is harmless, but they breed quickly, so it pays to act early.

Growing any of these? See our guides to tomatoes, lettuce, beans, cabbage, rocket and coriander.

How do I manage them safely?

1. Blast them off with a firm spray of water. Many will not find their way back.
2. Squash small clusters with a gloved finger.
3. Bring in the predators. Ladybirds and lacewings eat aphids in large numbers, and companion planting attracts them.
4. Try insecticidal soap or neem oil. Both are garden-safe. Spray in the cool of the morning or evening, and avoid open flowers so you do not bother bees.

We do not recommend harsh synthetic sprays for aphids on food plants. The gentle options above clear them up without the risks. For the full picture, see our guide to managing pests safely.

How do I prevent it?

Healthy, unstressed plants attract far fewer aphids. Consistent watering and the right plant for the season make a real difference, and our free garden calendar helps you get the timing right.

Plan your patch: our free garden calendar shows what to plant now where you live. Ready to grow? Browse our raised garden beds or build your own with the garden bed builder.

Image: Alvesgaspar, CC BY-SA 3.0, via Wikimedia Commons.