Currant Aphids is a minor pest that affects blackcurrants and redcurrants in Scotland. Here is what it looks like, how to spot the damage, and which controls have been tested.
What does it look like?
Three separate species cause this: the currant-sowthistle aphid is green with pale legs at 2-3mm, the currant blister aphid is yellow at 1.5-2.5mm, and the permanent currant aphid is dark green or black at around 2.3mm. All three are small enough that the damage they leave behind is usually what identifies them, not the aphid itself.
What causes it
Two of the three species need a second host plant nearby to complete their year: the currant-sowthistle aphid needs sowthistle, a common tall yellow-flowered garden weed, and the currant blister aphid needs hedge woundwort, a low purple-flowered weed often found at the edge of borders. A garden with either weed growing near the currants gives those two species somewhere to retreat to for summer, rather than needing to travel far to keep the cycle going.
Is this pest active now?
Check year-round for the permanent currant aphid. The currant-sowthistle and currant blister aphids are worth checking for specifically in spring and again in autumn, when they're actually present rather than away on their summer host.
Symptoms
Each species leaves a different mark: the currant-sowthistle aphid causes distorted leaves with yellowish mottling, the currant blister aphid puckers leaves into reddish or yellowish blisters at the shoot tips, and the permanent currant aphid stunts and compresses the shoot tips themselves. Heavy feeding from any of the three can coat nearby fruit in honeydew, inviting sooty mould that affects how the fruit looks without damaging the fruit itself.
Life cycle
All three species overwinterKeeping a plant alive and intact through the cold months, whether left outdoors, moved under cover, or stored dormant. Full definition → as eggs laid on the currant stems the previous autumn, hatching in spring around March to April to start the cycle again.
Why this matters in Scotland
These aphids occur in gardens across northern Britain, and unlike big bud mite on the same bushes, they're not known to spread any plant virus while they feed.
Big bud mite and the reversion virus it carries force a bush to be dug up and replaced. These aphids cost some leaf distortion and occasionally honeydew on the fruit, a real difference in scale on the same crop.
Controls: what actually works
All the methods below are backed by real evidence, not just repeated folklore.
Hand removal: squash or wipe off small colonies
Colonies are usually small and localised enough that direct removal by hand deals with them before they spread across the plant.
Natural predators: encourage ladybirds, hoverflies, parasitoid wasps and earwigs
All four are named as natural enemies that feed on aphids generally, and a garden that doesn't reach for a spray gives them the chance to do that job.
Myths about currant aphids
3 common claims about currant aphids, checked: 2 busted1 disputed0 untested0 hold up
“Blistered, puckered leaves on a blackcurrant or redcurrant bush need to be cut off to stop the damage spreading and protect the harvest”
The red and yellow blistering on currant leaves is caused by the currant blister aphid feeding at the shoot tips, and cropping usually remains unaffected by it. Management for all three currant aphid species is built around squashing small colonies by hand and encouraging predators like ladybirds and hoverflies, not stripping affected foliage. Once a leaf is already blistered, the aphids that caused it have typically moved to feed on newer growth nearby, so removing the older leaf mostly costs the bush healthy leaf area for no real gain.
What to do: Check new growth for small colonies through spring and squash or wipe them off by hand rather than cutting out already-blistered leaves, and leave the bush's natural predators to do the rest.
1 source
- RHS, Currant aphidsCropping usually remains unaffected by the currant blister aphid, and control relies on tolerating populations, monitoring, hand-squashing colonies and encouraging natural predators rather than removing damaged foliage.
“Currant bushes need spraying with an insecticide once aphid colonies are spotted, or the infestation will keep building”
No chemical control is recommended for any of the three currant aphid species; they're part of a garden's normal biodiversity that usually doesn't need eliminating. James Hutton Institute's own monitoring in northern Britain separately confirms these aphids aren't known to transmit any plant virus, which removes the disease-spread justification some gardeners reach for when deciding to spray. Spraying also works against the bush by killing off the ladybirds, hoverflies, parasitoid wasps and earwigs that are the natural predators keeping colonies in check.
What to do: Skip the spray, squash small colonies by hand where they're dense enough to worry about, and let predators established in the garden handle the rest.
2 sources
- RHS, Currant aphidsNo specific chemical control is recommended for currant aphids; management relies on tolerance, hand-squashing colonies and encouraging natural predators such as ladybirds, hoverflies, parasitoid wasps and earwigs.
- James Hutton Institute, fruitdisease.hutton.ac.uk, Ribes pestsSeveral aphid species colonise currants in northern Britain, and most damage leaves but are not known to transmit any viruses.
“Currant aphids feeding on the leaves will noticeably cut the size of the currant harvest”
This depends on which of the three currant aphid species is involved. Cropping usually remains unaffected by the currant blister aphid, and the permanent currant aphid does not normally affect the crop either, but the currant-sowthistle aphid is the one of the three which may affect cropping. A blanket claim that currant aphids reduce yield is true for one species and false for the other two on the same bush.
Our read Because the claim as usually repeated does not name a species, it reads as broader than the evidence supports for two of the three aphids involved, which is why this lands as disputed rather than a straight bust.
What to do: Identify which currant aphid is present before worrying about yield: distorted, yellow-mottled leaves point to the currant-sowthistle aphid, the one capable of affecting cropping, while blistered leaves or compressed shoot tips from the other two species are more likely to stay a cosmetic problem.
1 source
- RHS, Currant aphidsThe currant-sowthistle aphid is the only currant aphid which may affect cropping, while cropping usually remains unaffected by the currant blister aphid and the permanent currant aphid does not normally affect the crop.
Frequently asked questions
What should I do first if I find currant aphids in my garden?
Start with hand removal. After that, natural predators.
Will currant 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.
When are currant aphids most active in Scotland?
Check the seasonal activity section above. Scottish timings can run a few weeks behind the UK-generic figures.
Should I just leave currant aphids alone?
In most gardens, yes. currant aphids are food for birds, wasps and predatory insects, and a healthy garden carries some without trouble. Tolerance is also RHS's official position now, for that same reason.
Sources
2 sources, recorded with what each was used for
- RHS1: identification of all three species, symptoms, life cycle and host migration, hand removal, encouraging predators, absence of a specific chemical control
- James Hutton Institute2: confirming presence in northern Britain specifically, absence of virus transmission, honeydew and sooty mould risk on fruit, breeding programmes screening for resistant genotypes