Aphids are everywhere, and that is fine. They very rarely kill a plant, and they are a vital food for ladybirds, hoverflies and birds. This page covers which ones matter, what the damage looks like, and why the best first move is usually doing nothing.
What does it look like?
Sap-sucking true bugs, 1-7mm long. Green, black, yellow, pink, white or mottled. Some species cover themselves in white waxy secretions.
🌱 Plants at risk
Aphids also affects these crops in our grow guide:
Symptoms
Stunted growth with curled or distorted leaves; honeydew secretion that attracts sooty moulds; white cast skins accumulating on leaves; and transmission of plant viruses, a particular concern for soft fruit and vegetables. They very rarely kill plants.
Controls: what actually works
Every method below is graded by evidence, not by how often it gets repeated. Where a claim has been tested and failed, we say so plainly.
Tolerate them
RHS: 'Tolerate aphids where possible. It is usual to have some in a healthy, balanced garden.' Aphids very rarely kill plants, and predator populations naturally bring them under control through spring and summer.
Listing 'do nothing' as the first control is not a cop-out. It is what the primary authority recommends, and no competitor leads with it.
Encourage natural enemies — ladybirds, ground beetles, hoverflies, parasitoid wasps, earwigs
All five are aphid predators. Encourage them, and let predator populations bring aphid numbers under control through spring and summer.
Squash colonies by hand
Squash colonies between finger and thumb.
Pesticides
RHS: 'No - The RHS recommends that you don't use pesticides', because they reduce biodiversity and harm soil health.
Companion planting: nasturtiums as a trap crop for blackfly on beans
Garden Organic presents it as effective, but as practice rather than trial data.
Scottish grower notes
Cabbage aphid — the aphid that most troubles brassicas — is generally less of a problem in Scotland than further south. It builds fastest in hot seasons, so Scotland's cooler summers are a genuine advantage for brassica growers.
On raspberries the key aphid is the large raspberry aphid (Amphorophora idaei), a virus carrier. The James Hutton Institute's Scottish raspberry breeding programme produced varieties with aphid-resistance genes, but the aphid has evolved to overcome the older gene (A1) and is now colonising plants with the newer gene (A10) — so bred-in resistance is weakening and shouldn't be relied on alone.
Frequently asked questions
What should I do first if I find aphids in my garden?
Start with tolerate them. After that, encourage natural enemies — ladybirds, ground beetles, hoverflies, parasitoid wasps, earwigs. The full list of evidenced controls is above, each graded by how much evidence supports it.
Will aphids kill my plants?
They rarely kill established plants. The damage is usually cosmetic on outer leaves, and natural predators often bring numbers under control without you doing anything.
Should I just leave aphids alone?
In most gardens, yes. aphids are food for birds, wasps and predatory insects, and a healthy garden carries some without trouble. Tolerance is also the official position now, and the stance box above sets out that reasoning in full.
Sources
4 sources, recorded with what each was used for
- RHS1: biodiversity framing and tolerance advice, identification (1-7mm, colours, waxy species, 500+ British species), damage including virus transmission, named predators, finger-squashing, explicit advice against pesticides
- Garden Organic8: nasturtium trap crop; predator-attraction principle
- SAC/SRUC13: cabbage aphid is less troublesome in Scotland's cooler climate — a counterbalancing advantage for brassica growing
- James Hutton Institute2: large raspberry aphid (Amphorophora idaei) as raspberry virus vector; Hutton raspberry breeding aphid-resistance genes A1/A10 being overcome by new biotypes