Key takeaways
- Woolly aphid shows up as fluffy white tufts on apple bark, never on the leaves
- Colonies appear from April, in bark cracks, pruning wounds and branch crooks
- Feeding leaves lumpy swellings that can split and let in apple canker
- Scrub colonies off with a stiff brush as soon as you see them, and check again weekly
- A tiny parasitic wasp, ladybirds and earwigs often keep numbers down by midsummer
- If you must spray, use an authorised insecticide labelled for apples, following the label
Fluffy white tufts on your apple tree’s bark, like bits of cotton wool, mean woolly aphid. These small sap-sucking insects hide under their own white wax. They won’t kill a healthy tree, but they leave lumpy swellings that can let in canker. The fix is simple and needs no spray: brush them off early, keep checking and let predators finish the job. Here’s how to spot them and clear them.
What does woolly aphid look like?
Look for white, fluffy patches on bark, in cracks, around pruning cuts and in the crooks of branches. They’re never on the leaves. Fresh colonies are bright white. Older ones look greyish and matted.
Rub a patch and you’ll find small, dark purple-brown aphids underneath. Crushed, they leave a reddish smear.
Apple is the main host. Woolly aphid also feeds on cotoneaster, pyracantha and hawthorn. If your pyracantha has white fluff along its stems, it’s very likely the same pest.
Woolly aphid on cotoneaster. The same pest moves between apples, cotoneaster and pyracantha.
Is it woolly aphid or something else?
A few other white pests turn up on plants. Here’s how to tell them apart.
| Pest | Where you find it | What it looks like |
|---|---|---|
| Woolly aphid | Bark of apple, cotoneaster, pyracantha | Fluffy white tufts, dark aphids underneath |
| Mealybug | Mostly houseplants and greenhouse plants | Small, white, mealy insects in leaf joints |
| Scale insect | Stems and leaf undersides | Smooth, brown or white bumps, little fluff |
| Powdery mildew | Leaves and shoot tips | Flat white powder, no insects |
Indoors, white fluff in leaf joints is more likely mealybug. Firm bumps on stems point to scale insects.
Pull back the fluff and you’ll see the dark aphids feeding on the bark underneath.
What damage does woolly aphid do?
The aphids suck sap from the bark. Where colonies feed year after year, the bark swells into lumpy, knobbly growths. These can split in winter frost, giving the fungus that causes apple canker a way in. The guide to canker in fruit trees explains what to do if that happens.
On young shoots, heavy attacks can stunt growth. Older, vigorous trees usually cope well. Small trained trees, such as cordons and espaliers, show the damage more because they have fewer branches.
Old feeding sites swell into knobbly lumps like this. Cracks in them can let canker in, so deal with colonies early.
When does woolly aphid appear?
Young aphids spend winter tucked into bark cracks and sometimes on the roots. They become active as the weather warms in April, and the white fluff appears soon after. Colonies grow through summer.
In late summer, some aphids grow wings and fly to new host plants. That’s how trees nearby pick it up. Colonies fade in autumn, but the young hide in the bark ready for next spring.
How to get rid of woolly aphid
Start early and keep at it. Small colonies are quick to clear.
A stiff old brush breaks up the wax and knocks the aphids off. Do it as soon as you spot the white fluff.
- Brush them off. Scrub each white patch with a stiff brush, such as an old washing-up brush or toothbrush. This breaks up the wax and knocks the aphids off.
- Prune out badly affected shoots. Cut out small, heavily infested twigs and bin them, as long as it suits the tree’s shape.
- Check weekly. New colonies keep appearing from April to September. Brush them off as soon as you spot them.
- Let predators help. A tiny parasitic wasp, Aphelinus mali, lives naturally in many UK gardens. It lays eggs inside the aphids, which turn black and die. Ladybirds, hoverfly larvae, lacewings and earwigs eat them too.
- Spray only as a last resort. If an infestation is heavy, use an authorised insecticide labelled for apples and woolly aphid, exactly as the label directs. Never spray open blossom, as it can harm bees.
Home-made sprays and solvents aren’t approved for killing pests, so stick to brushing and pruning. The guide to getting rid of aphids covers greenfly and blackfly on the leaves too.
Gardener’s tip: Spraying kills predators along with the aphids. On most garden trees, brushing plus a little patience gives better results by midsummer.
How to stop woolly aphid coming back
- Look at pruning cuts and bark cracks each spring, as that’s where colonies start.
- Check new trees and shrubs before planting, especially cotoneaster and pyracantha.
- Go easy on high-nitrogen feeds. Soft, sappy growth suits aphids.
- Encourage predators. Flowering plants nearby feed hoverflies and lacewings. The guide to attracting ladybirds has more ideas.
- Keep an eye on hedges of cotoneaster or pyracantha, which can feed colonies that move onto your apples.
Trained trees like these are easy to check from the path. Make a quick look along each branch part of your weekly routine.
Woolly aphid calendar
| Month | What to do |
|---|---|
| March | Check bark cracks, pruning cuts and branch crooks |
| April to May | Brush off the first white colonies as soon as they appear. Don’t spray blossom |
| June to July | Keep checking weekly. Look for black, parasitised aphids, a sign predators are working |
| August to September | Brush off late colonies. Winged aphids may be moving to new plants |
| Winter | Prune out small, badly swollen shoots and check for canker |
Common woolly aphid mistakes
Waiting until colonies are big. Small patches take seconds to brush off. Big ones take far longer and do more damage.
Spraying the fluff. Liquid runs off the wax and kills helpful insects. Brush first.
Using home-made remedies. Soapy water, solvents and other home mixes aren’t approved pesticides and can harm bark and predators.
Ignoring nearby hosts. A cotoneaster hedge full of woolly aphid will keep reinfesting your apples.
Brushing once and forgetting. New colonies appear all summer. Weekly checks keep on top of them.
More help with common pests is in the pest control hub.
Frequently asked questions
What is the best treatment for woolly aphid on apple trees?
Scrub the colonies off with a stiff brush as soon as you see them. Prune out badly affected shoots, check weekly and let predators help. Only use an authorised insecticide labelled for apples if numbers are high.
Why don’t aphid sprays work well on woolly aphid?
The white wax shields the aphids from sprays. Liquid tends to run off the fluff without reaching the insects underneath. That’s why brushing, which breaks up the wax, works so well.
What does woolly aphid damage look like?
Lumpy, knobbly swellings on the bark where colonies have fed. The swellings can split, letting in apple canker. Heavy attacks on young shoots can stunt them.
When should I treat woolly aphid?
As soon as the white tufts appear, usually from April. Small colonies are much easier to clear than big ones. Keep checking through summer, as new colonies keep appearing.
Does woolly aphid spread to other plants?
Yes, it can spread to nearby apples, cotoneaster and pyracantha. Winged forms fly in late summer. Check new plants before you buy and keep an eye on neighbouring hosts.
Is woolly aphid harmful to people or pets?
No, it doesn’t bite or sting and isn’t harmful. It just damages the bark of the trees and shrubs it feeds on.
Keep your trees strong and easy to check with the guide to growing apple trees in the UK.
Our team produces practical UK gardening guidance from source research, contributor records and established horticultural practice. Editorial standards are overseen by Matt W.
